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, officials said.

The bomb in the city of Kaduna appeared to have been transported by two people on a motorcycle. One official said both riders were killed along with a passerby.

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.

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.

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

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.