Contest attackers 'probably inspired by IS'

The Islamic State group claimed responsibility on Tuesday for the assault on a Texas cartoon contest that featured images of the Prophet Muhammad. But counterterrorism experts said IS has a history of asserting involvement in attacks in which it had no operational role.

That suggests the two gunmen could have carried out their own lone-wolf-style strike before they were shot dead at the scene of Sunday's shooting in the Dallas suburb of Garland.

The evidence does not indicate the attack was directed by the Islamic State, "but rather inspired by them", said Republican Michael McCaul, chairman of the House Homeland Security Committee, who was briefed on the investigation by federal law enforcement officials. "This is the textbook case of what we're most concerned about."