Egyptian police have detained 200 people for questioning over two attacks on foreigners in the capital on Saturday.
Police launched the roundup just north of Cairo, looking for members of a group believed responsibile for the attacks and for a Cairo bombing that killed three tourists in April.
Police say they were chasing a suspect in the April 7 bombing on Saturday, when he detonated explosives as he jumped off a bridge near Cairo's Egyptian Museum. Four foreigners and three Egyptians were wounded in the blast.
A short while later, two veiled women related to the suspect fired on a tour bus near Cairo's Citadel, before being shot dead by police. No bus passengers were hurt.
The U.S. Embassy said Americans should avoid Cairo's tourist sites until it can evaluate the security situation.
Some information for this report provided by Reuters, AP and AFP.