Story highlights

Bomb explodes under a bus in Gombe, Nigeria, police say

People were boarding the bus when the blast happened, police say

No one has claimed responsibility

A different explosion killed seven people at a market in Bauchi, Nigeria

CNN  — 

At least 20 people were killed Monday when an explosion rocked a bus station in the northeast Nigerian city of Gombe, which has recently come under repeated attacks blamed on Boko Haram insurgents, officials said.

The incident happened when a homemade bomb planted near a bus exploded as people were boarding ‎at the Dukku bus station, triggering a fire that consumed vehicles, authorities said.

No one immediately claimed responsibility for the blast.

“So far, 20 people have been killed in the explosion and another 18 were badly injured,” said Mato Yakubu, Gombe state director of the National Orientation Agency (NOA).

An official with the Nigerian Red Cross in the city said 20 bodies were evacuated to a local morgue.

Later Monday, an explosion tore through a crowded market in the northern Nigerian city of Bauchi, killing 17 people and injuring 42 others, officials said.

It wasn’t immediately clear whether a bomb caused the Bauchi explosion, police said.

The blast happened at about 5:30 p.m. (11:30 p.m. ET) in a section populated by cosmetics and blouse shops, causing a fire that spread to other parts of the market.

“(An) investigation is in progress to ascertain (the) cause of the explosion and level of damage to property,” Bauchi state police spokesman Haruna Mohammed said.

Bauchi is about 150 kilometers (93 miles) west of Gombe.

Northern Nigeria, especially northeastern Nigeria, has been targeted regularly by Boko Haram since 2009. The Islamist militant group has fought an anti-government campaign to institute Sharia, or Islamic law, attacking police, schools, churches and civilians, and bombing government buildings.