An FBI crime scene investigator works May 4 at the scene in Garland, Texas, where two gunmen were shot and killed after they opened fire on a security officer outside a provocative contest for cartoons of the prophet Muhammad.

FBI investigators stand near an apartment being searched on Monday in Phoenix, believed to be the home of one of two gunmen who were shot and killed the night before outside a venue hosting an exhibit about the prophet Muhammad in Garland, Texas.

An FBI agent views the area where a car linked to a shooting incident in Garland, Texas, was blown up by police as a precaution on May 4.

A police officer stands guard at a parking lot near the Curtis Culwell Center.   (LM Otero / Associated Press)