Abuja, March 11 (IANS): At least four people were killed and 20 injured in a blast in northern Nigeria's Borno state on Tuesday, according to media reports.

The blast occurred in Maiduguri, the capital of the Borno state, around 4 pm, Xinhua reported citing a senior medical staff. The source added that some of the injured victims had sustained severe burns.

The report did not immediately name the perpetrators of the attack, but the state of Borno is known to be facing the brunt of the Boko Haram terrorist group, which has been a major security threat in Nigeria -- Africa's most populous country -- since 2009.

According to a witness, people rushed for safety as the blast shook buildings in the area.

The blast on Tuesday occurred three days after multiple explosions killed 54 people and injured 38 in the city.

On Tuesday, Boko Haram fighters also attacked the Ngamdu village in the Borno state and a witness revealed that countless gunshots were heard in the village.

Last week, Boko Haram militants had attacked the village and killed at least six people, in an attack that lasted several hours.

Nigerian troops killed scores of Boko Haram militants in the northeast Nigerian state of Adamawa, where emergency was imposed, the country's military said on Tuesday.

The Boko Haram insurgency has been most intense in the Nigerian states of Borno, Yobe and Adamawa.

The militant group, which has owed allegiance to the Islamic State (IS) terrorist group, has also proved to be a threat for Nigeria's neighbouring countries -- Cameroon, Niger and Chad.

The group, whose name in the local dialect translates into "Western education is sin", seeks to impose the Islamic Sharia law in the Nigerian constitution.