(CNN)A man with a gun 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.
It's been an emotionally charged few days across the country because of the protests stemming from the Alton Brown shooting, and the ambush on Dallas police officers where a sniper killed five officers.
"We can't take anything for granted any more," East Baton Rouge Sheriff Sid Gautreaux said last week.

God help us