Boko Haram militants killed five people in two separate attacks in the northeast Nigerian city of Gombe Sunday, witnesses said.

One of the attacks, by a suspected suicide bomber, targeted a military checkpoint in the Kasuwar Katako area of the city, while the other targeted a local market, a witness said, according to a Xinhua report.

Three people, including a soldier, died in the suicide bomb attack on the military checkpoint, while two people died in the market explosion, another witness said.

Locals suspect the attack to be the handiwork of the Boko Haram, which had carried out similar attacks earlier Sunday in the northeastern Borno and Yobe states.

At least 12 people were killed earlier in the day, as government forces resisted multiple attacks by Boko Hara militants in Maiduguri city, the capital of Nigeria's Borno state, according to media reports.

In a related development, the Nigerian military said Sunday that its troops in the northeastern part of the country captured a massive cache of arms and ammunition belonging to the militants, from different locations of the Borno state, following mop-up operations, according to a Xinhua report.

Activities of the Boko Haram group have been on the increase in Borno, a state which shares its borders with Cameroon, Niger and Chad.

Boko Haram has proved to be a major security threat in Nigeria since 2009. The group seeks to enshrine the Islamic Sharia law in the Nigerian constitution and create an Islamic state in the mainly Muslim northern part of Nigeria.

More than 13,000 people have been killed and over a million made homeless in violence perpetrated by the insurgent group since 2009.