An explosion that devastated a bus in Armenia's capital, killing two people and injuring seven, was not the result of a terrorist attack, the country's investigative committee said Tuesday.

The explosion occurred Monday evening on the streets of Yerevan several miles northwest of the city's central square. Local news websites showed photos of a gutted bus with shattered windows.

An investigator told The Associated Press that one of the passengers had quarreled with relatives and told friends that he planned to seek revenge by handing them an explosive device. That device may have detonated early on the bus while being brought to its intended destination, the investigator said, speaking on condition of anonymity because he was not allowed to reveal details about the investigation.

Sona Truzyan, a member of the investigative committee, told the AP that investigators have ruled out the possibility that the explosion was caused by a terrorist attack.

Armenia's chief of police, Vladimir Gasparyan, said the explosion was inside the bus and it was not a diesel fuel explosion or a gas cylinder leak, according to Armenian news reports.