North-central Nigeria has suffered from a spate of attacks by unidentified militants across the neighboring states of Kaduna and Niger and the national capital region of Abuja in recent days, with gunmen separately attacking an airport, major rail line, and Christian villages, local media reported on Tuesday.

“Forty-eight hours after attacking the Kaduna airport, killing an aviation worker and injuring many others, terrorists, yesterday, escalated their attacks by bombing an Abuja-Kaduna train, with some 970 passengers onboard,” Nigeria’s This Day newspaper reported on March 29.

Health workers at a Kaduna hospital treating survivors of Monday’s doomed train trip told the BBC on Tuesday at least seven people were killed during the attack on the rail line, which runs from the central Nigerian capital of Abuja to the northern city of Kaduna. In addition, at least 22 people were injured in the incident, according to the same anonymous hospital sources.

The train’s attackers, whose identities remain unknown, “used explosives to first blow up the rail track before opening fire on the train,” according to Fidet Okhiria, the chief executive of the state-owned Nigerian Railway Corporation.

“Many people are also feared to have been abducted,” he said on March 29, as quoted by the Associated Press (AP).

“They bombed the track and started exchanging fire with the security inside the train,” a survivor of the attack named Abdulwadud Ahmad told the AP. “They subdued the security, then came into the train and kidnapped a lot of people.”

“No group has claimed responsibility for the attack but suspicion quickly fell on the armed groups who have carried out thousands of abductions and killings in the northwest and central states of the West African nation,” the AP noted on Tuesday.

The news agency referred to the actions of Boko Haram, a jihadist organization based in northeastern Nigeria since 2009 that has terrorized the region since then through mass kidnappings and massacres. The group has experienced a resurgence over the past two years and crept closer to the central Nigerian capital of Abuja in recent months.

In the Munya region of Niger state, which borders both Kaduna state and Abuja, another attack on civilians by an unidentified group of gunmen occurred on the night of March 27.

“An unspecified number of villagers have been killed in several communities in the Munya Local Government Area of Niger State when terrorists invaded their villagers between Sunday afternoon [March 27] and early Monday morning [March 28],” This Day reported on March 29.

“In addition, the terrorists also kidnapped a catholic priest Reverend Leo Raphael Ozigi and some clergymen who ran into the gunmen as they were returning to Minna [village] after the Sunday mass held in one of the communities,” the newspaper relayed.