Baltimore - Baltimore police officers responding to the sound of gunshots near an apartment building fatally shot a man who fired at them with an "AR-15-style" gun, authorities said early on Friday.No officers were wounded nor anyone else in the shooting Thursday night in a neighbourhood on the city's west side, police spokesperson TJ Smith said. He added at a news briefing that it wasn't immediately clear why the man had begun shooting.Four plainclothes officers riding in an unmarked car heard gunfire coming from the building on the city's west side on Thursday night, Smith said. The officers drove toward the sound and when they arrived, they saw a man shooting an "AR-15-style" gun, according to Smith.The shooting comes a week after police shootings of two black men, one in Louisiana and the other in Minnesota, stoked outrage among many in the African-American community and protests around the country. Tensions were also heightened around the nation by last week's killing of five police officers in Dallas by a black gunman.The man started firing toward the officers, and two returned fire, Smith said. The suspect was shot at least once and retreated to the apartment building, according to Smith.‘Theory’Officers, who Smith said initially thought there was more than one suspect involved, surrounded the building and searched the scene.He said authorities found the gun in a tree line just behind the apartment complex and the suspect inside with at least one bullet wound to his upper body. The man, who wasn't immediately identified, was taken to a hospital, where he was pronounced dead, he said."We don't have a victim... No one has come forward and said, 'Hey, I was being shot at’," he said.The idea that the man was trying to lure officers to the scene with the gunfire is a "theory" police are looking into, Smith said."Officers were drawn due to gunfire, were they specifically drawn there by him if they might have known they were in the area? We don't know the answer to that yet," Smith said.While the officers were in plainclothes, they were also wearing outer vests that were marked "police" on the front and back, he said.Smith said an investigation was opening but he didn't immediate identify the officers, the man or the races of those involved. He said the officers who fired their weapons were being place on administrative duties as is routine in such cases.Smith said he got close to the scene and added investigators were spending early on Friday working the crime scene."There are a number of shell casings from this AR-15-style weapon on scene," he said.He also said police were asking anyone in the area about the time of the shootings to come forward to help investigators.