KADUNA, Nigeria -- Three people were killed in a bomb blast Tuesday on a northern Nigerian road leading to a mosque where a cleric had condemned the Islamist militant group Boko Haram, police and other officials said.

"About 3.50 p:m, two men on a motorcycle carrying what was suspected to be an improvised explosive device were killed when the device exploded while they were in motion along Ali Akilu road," Kaduna police spokesman Abubakar Balteh said. "One other passerby was also killed in the explosion."

Red Cross official Shehu Umar Abdul also said the two bombers and a passerby were killed.

It was unclear whether the suspects were headed toward the mosque, which is located about a five-minute drive from the blast.

There was no confirmation of what the target may have been, or if the device went off accidentally.

"We still don't know where they were headed and the scene of the blast was not near any mosque," Balteh said.

The cleric at the mosque had also recently invited Christians to break the Ramadan fast with Muslims this weekend.

"We were informed that some people riding on a motorcycle dropped an explosive device," said Musa Ilallah, an official with the National Emergency Management Agency.

Kaduna, a major city in the country's north, has been hit by numerous attacks blamed on Boko Haram, which is accused of killing more than 1,400 people since 2010 as part of its insurgency in northern and central Nigeria.