tonight, what we now know about where the bombs were made. james longman in sri lanka again tonight. reporter: tonight, sri lanka on high alert as u.s. officials warn of ongoing terrorist plots. investigators keying in on surveillance footage from the moments just before the deadly attacks. images broadcast on sri lankan tv from the cinnamon grand hotel show a man in a backpack lingering in the dining room. minutes later, an explosion tears through the crowded restaurant. hours after the first explosions, a tip led police here. this is a safe house in colombo which is believed to have been used by at least some of the suicide bombers. a woman detonated her suicide vest, killing three officers, and her two children. according to police sources, the identical bombs may have been made in this copper factory, possibly by one bomb maker. isis says this photo shows the attackers. the man at the center, a key operative known as zahran hashmi. his name right here on an