The FBI released photos on Thursday of two suspects in the Monday bombing of the Boston Marathon that killed three people and injured 176.

The two men are both wearing baseball caps and carrying backpacks, and the FBI said it has video of one of the men leaving his backpack near the site of one of the explosions.

“We consider them armed and extremely dangerous. No one should approach them,” FBI Special Agent Rick DesLauriers said in a briefing. “No one should attempt to apprehend them except law enforcement. Let me reiterate that caution, do not take any action on your own. If you see these men, contact law enforcement.”