Baton Rouge: 'Three US police officers shot dead and 7 injured

A man with a gun reportedly opened fire on police officers in Baton Rouge on Sunday, injuring at least seven -- including three who are feared dead, an official said.

Police received a call of "suspicious person walking down Airline Highway with an assault rifle," a source with knowledge of the investigation told CNN. When police arrived, the man opened fire.

The remaining officers are hospitalized in critical condition, the source said.

The victims were from Baton Rouge Police Department as well as East Baton Rouge Parish Sheriff's Office, another official said.

Since the shooting death of Alton Sterling by Baton Rouge police earlier this month, the department has worried about credible threats against officers.