Three policemen and five militants were killed on Monday by a car suicide bomb at a checkpoint on the outskirts of Damaturu, capital of Yobe state in northern Nigeria, a police spokesman said.
The checkpoint is on a highway that connects the city with Borno state capital Maiduguri. The road and villages along it are frequently hit by bombs or raids by suspected members of Islamist jihadi group Boko Haram.
"We were stopped by the army at a checkpoint. There was an SUV (sport utility vehicle) about five cars away from us. I believe two people were in that car. ... One came out and suddenly there was a loud sound and smoke filled the air," Ahmed Mohammed, who was driving toward Damaturu from Maiduguri, said.
Police spokesman Toyin Gbadegasin said that three of the people killed were policemen and the remainder were militants. He said police had intercepted two cars loaded with explosives and then the SUV blew up.
On Thursday, at least nine people were killed in Damaturu by a young female suicide bomber as worshippers gathered to mark the Muslim holiday Eid al-Fitr. Fifty people were killed by bombs on Friday in another northeastern city, Gombe.
Boko Haram controlled a swath of land around the size of Belgium at the end of 2014, but were pushed out of most of that territory by Nigerian troops, with military help from neighboring Chad, Niger and Cameroon.
But while they are dispersed, the militants are still able to carry out attacks in northern Nigeria and neighboring countries.
President Muhammadu Buhari has flown to the United States and is due to meet with President Barack Obama to discuss increased U.S. military assistance to quash the insurgency.