Law enforcement personnel work at the scene of a shooting where five Houston police officers were reported shot Jan. 28, 2019 in Houston, Texas.

Four Houston police officers were shot on Monday as they attempted to serve a warrant in a narcotics investigation and two suspects were shot dead, the city's police chief said.

Two of the officers were shot in the neck and were undergoing surgery, Houston Police Chief Art Acevedo told reporters, adding that they were in critical but stable condition. The other two officers shot will remain hospitalized for at least another 24 hours, but are ambulatory, he said.

The officers were shot when they tried to enter a home in southeast Houston to serve a warrant shortly before 5 p.m., Acevedo said.

"Immediately upon breaking the door the officers came under fire from one or more suspects in the house," said Acevedo, adding that the officers were shot with semi-automatic pistols.

A SWAT team took over the scene and sent in two robots to check the home.

Images from the robots showed two suspects had been struck by return gunfire from police. They were pronounced dead at the scene, Acevedo said.

He said that a fifth police officer suffered a knee injury during the gun battle.

The investigation began after a neighbor told police that the suspects were dealing black tar heroin out of the home, Acevedo said.