Kano, Nigeria(CNN) More than 50 people were killed and scores wounded in a series of suicide bombings in northern Nigeria on Saturday, witnesses and authorities told CNN.
The blasts occurred in Maiduguri, the capital of the tumultuous Borno state, at the city's main market, a fish market and a bus station.
Four suicide bombers -- three women and a man -- carried out the attacks, according to witnesses.
No group immediately claimed responsibility for the bloodshed. But the Islamist extremist group Boko Haram has been behind many similar attacks in northern Nigeria and beyond, killing hundreds in recent months as part of its terrorist campaign to bring its twisted version of Sharia law to the region.
Clement Adoda, a Borno state police spokesman, said at least 54 people were killed and another 139 wounded in the suicide attacks.
Suleiman Bulunkutu said he and others involved in the rescue operation had taken about 50 bodies to the Maiduguri General Hospital morgue.
"This toll doesn't include those taken to three other hospitals," Bulunkutu said. "Therefore, the final (death) toll may be higher."
In the first blast, a woman dressed in a hijab got off a motorized rickshaw and blew herself up outside the Baga Road fish market around 11:20 a.m. (5:20 a.m. ET), fish trader Mohammed Boni said.
The next attack took place about an hour later outside Monday Market, the main one in the city, where people were lined up to go through security. Those measures -- in which people are checked for explosives and guns -- were set up because of the spate of Boko Haram attacks in the city and region.
Two women joined the female security line, one of whom "blew herself up, causing minimal casualty," said witness Abdulkarim Musa.
Then, as people gathered to help, the second woman detonated her explosives, said Musa, who was waiting outside the market in the male security line.
The third attack occurred at a bus station.
"He came in our midst near the bus station and pressed a remote device he was holding in his hand," a wounded survivor who requested anonymity for his personal safety said from Maiduguri General Hospital.
Such attacks, sadly, are nothing new for Borno State, one of those hit hardest by Boko Haram and the Nigerian military's campaign to stop them.
The terrorist group has not only bombed crowded markets but attacked churches and mosques, raided villages, and kidnapped people young and old -- most famously the more than 200 girls taken last April from a school in Chibok.
Boko Haram: Nigeria's crisis
A video of Abubakar Shekau, who claims to be the leader of the Nigerian Islamist extremist group Boko Haram, is shown in September 2013. Boko Haram is an
Islamist militant group waging a campaign of violence in northern Nigeria. The group's ambitions range from the stricter enforcement of Sharia law to the total destruction of the Nigerian state and its government. Click through to see recent bloody incidents in this strife-torn West African nation:
Bodies lie in the streets in Maiduguri, Nigeria, after religious clashes on July 31, 2009. Boko Haram exploded onto the national scene in 2009 when
700 people were killed in widespread clashes across the north between the group and the Nigerian military.
An official displays burned equipment inside a prison in Bauchi, Nigeria, on September 9, 2010, after the prison was attacked by suspected members of Boko Haram two days earlier. About
720 inmates escaped during the prison break, and police suspect the prison was attacked because it was holding 80 members of the sect.
Nigerian President Goodluck Jonathan, second from left, stands on the back of a vehicle after being
sworn-in as President during a ceremony in the capital of Abuja on May 29, 2011. In December 2011, Jonathan declared a
state of emergency in parts of the country afflicted by violence from Boko Haram.
Rescue workers help a wounded person from a U.N. building in Abuja, Nigeria, on August 26, 2011. The building was rocked by a bomb that killed at least 23 people, leaving others trapped and causing heavy damage. Boko Haram had claimed responsibility for the attack in which a Honda packed with explosives
rammed into the U.N. building, shattering windows and setting the place afire.
A photo taken on November 6, 2011, shows state police headquarters burned by a series of attacks that targeted police stations, mosques and churches in Damaturu, Nigeria, on November 4, 2011. Attackers left scores injured --
probably more than 100 -- in a three-hour rampage, and 63 people died.
Men look at the wreckage of a car after a bomb blast at St. Theresa Catholic Church outside Abuja on December 25, 2011. A string of bombs struck churches in five Nigerian cities,
leaving dozens dead and wounded on the Christmas holiday, authorities and witnesses said. Boko Haram's targets included police outposts and churches as well as places associated with "Western influence."
A paramedic helps a young man as he leaves a hospital in the northern Nigerian city of Kano on January 21, 2012. A spate of bombings and shootings left more than 200 people dead in Nigeria's second-largest city. Three days later, a joint military task force in Nigeria
arrested 158 suspected members of Boko Haram.
A photo taken on June 18, 2012, shows a car vandalized after three church bombings and retaliatory attacks in northern Nigeria killed at least 50 people and injured more than 130 others, the Nigerian Red Cross Society said.
A French family kidnapped February 19, 2013, in northern Cameroon is
released after two months in captivity in Nigeria. The family of four children, their parents and an uncle were kidnapped in Waza National Park in northern Cameroon, situated near the border with Nigeria. One of the captive men read a statement demanding that Nigeria and Cameroon free jailed members of Boko Haram.
A soldier stands in front of a damaged wall and the body of a prison officer killed during an attack on a prison in the northeastern Nigerian town of Bama on May 7, 2013. Two soldiers were killed
during coordinated attacks on multiple targets. Nigeria's military said more than 100 Boko Haram militants carried out the attack.
A deserted student hostel is shown on August 6, 2013, after gunmen
stormed a school in Yobe state, killing 20 students and a teacher, state media reported.
A photograph made available by the Nigerian army on August 13, 2013, shows improvised explosive devices, bomb-making materials and detonators seized from a Boko Haram hideout. Gunmen attacked a
mosque in Nigeria with automatic weapons on August 11, 2013, killing at least 44 people.
Nigerian students from Jos Polytechnic walk on campus in Jos, Nigeria, on September 30, 2013. Under the cover of darkness,
gunmen approached a college dormitory in a rural Nigerian town and opened fire on students who were sleeping. At least 40 students died, according to the News Agency of Nigeria.
Soldiers stand outside the 79 Composite Group Air Force base that was attacked earlier in Maiduguri on December 2, 2013.
Hundreds of Boko Haram militants attacked an Air Force base and a military checkpoint, according to government officials.
Catholic priest Georges Vandenbeusch speaks to reporters outside Paris after his release on January 1, 2014. Vandenbeusch was snatched from his parish church in Cameroon on November 13. Boko Haram claimed responsibility for kidnapping the priest.
A man receives treatment at Konduga specialist hospital after a gruesome attack on January 26, 2014. It was suspected that Boko Haram militants opened fire on a village market and
torched homes in the village of Kawuri, killing at least 45 people.
Police officers stand guard in front of the burned remains of homes and businesses in the village of Konduga on February 12, 2014. Suspected Boko Haram militants
torched houses in the village, killing at least 23 people, according to the governor of Borno state on February 11.
Yobe state Gov. Ibrahim Gaidam, left, looks at the bodies of students inside an ambulance outside a mosque in Damaturu. At least 29 students died in an
attack on a federal college in Buni Yadi, near the capital of Yobe state, Nigeria's military said on February 26, 2014. Authorities suspect Boko Haram carried out the assault in which several buildings were also torched.
Rescue workers try to put out a fire after a bomb exploded at the busiest roundabout near the crowded Monday Market in Maiduguri on July 1, 2014.
Police in riot gear block a route in Abuja on October 14, 2014, during a demonstration calling on the Nigerian government to rescue schoolgirls kidnapped by Boko Haram. In April, more than
200 girls were abducted from their boarding school in northeastern Nigeria, officials and witnesses said.