Three police officers were shot dead and three others were wounded in Baton Rouge, La., on Sunday morning. The single gunman was killed, the authorities said. The area where the shooting took place has been the scene of protests in the weeks since the police shooting of Alton B. Sterling on July 5.

Around 8:40 a.m. on Sunday, the police in Baton Rouge were responding to report of a man with a gun dressed in black walking near the Hammond Aire Plaza shopping center on Airline Highway. In a confrontation that lasted less than 10 minutes, three officers were killed and three others were wounded, officials said.

 Kip Holden, the mayor-president of East Baton Rouge Parish, said that the suspect was Gavin Long of Kansas City, Mo.

 Mr. Long is believed to have been the only gunman, the police in Baton Rouge said at a news conference, despite earlier reports of two others at large. Col. Mike Edmonson, the superintendent of the Louisiana State Police, said there was “no active shooter scenario going on in Baton Rouge.”

The slain officers were a 41-year-old and a 32-year-old with the Baton Rouge Police Department, and a 45-year-old deputy with the East Baton Rouge Parish Sheriff’s Office.

According to the authorities, a 41-year-old sheriff’s deputy is in critical condition; a 51-year-old deputy was undergoing surgery for injuries that were not life threatening; and a 41-year-old Baton Rouge police officer was hospitalized with injuries that were not life threatening.

At the time of the shooting, a plot against the police had been under investigation after a burglary suspect said he wanted to harm officers.

The White House said that President Obama had been briefed and that federal officials were in touch with the local authorities. In a statement, Mr. Obama characterized the shooting as a “cowardly and reprehensible assault.”

The police plan to hold another news conference on Monday at 1 p.m.