New Haven Officer Joseph Avery says police don't know if the suspects planned to use the explosives, because they're not talking much to investigators. Police haven't released their names yet.
Officers say they stopped the car Tuesday night and found pipe bombs, rifles and a propane tank.
Authorities closed off a four-block area, but didn't order an evacuation. A bomb squad detonated the explosives without incident.
There were no reports of any injuries.