A Houston police officer was shot Thursday afternoon, but escaped serious injury, while responding to a complaint about a person firing a gun inside a southwest Houston apartment, officials said. Around 12:44 p.m., officers were dispatched to an apartment in the 10200 block of Forum Park Drive, because of complaints about a suspicious person with a weapon and about a person firing a gun, Houston Police Department Executive Assistant Chief Larry Satterwhite said. An anonymous 9-1-1 caller had given dispatchers a unit number, but when three officers arrived at the scene, they weren't sure if that unit belonged to the caller or the person firing a gun, Satterwhite said. When one of the officers approached the unit, a man opened the door and fired one shot at the officer, Satterwhite said. The officer, a 15-year-veteran of the department, was grazed in the right forearm, Satterwhite said. He ran for cover and fired his own gun toward the man in the apartment, as the man closed the door and went back inside. Soon after, the man came out of the apartment unarmed and was arrested. The man wasn't injured, Satterwhite said. "Our officer was just trying to figure out what was going on and the door opened and it appears the suspect just started firing," Satterwhite said. The wounded officer "appears to be OK, but was seriously shaken up," Satterwhite said. "We're very thankful that he's OK." The name of the officer and of the man who was arrested weren't immediately released. Satterwhite said officers had been called about the man at least four times before, including one call about a man having a possible mental health crisis. It's unclear if any of the previous calls involved a gun or if there was anything in the man's history that prohibited him from owning a legal gun, Satterwhite said. The department's homicide special investigation unit and the Harris County District Attorney's Office were investigating the shooting, Satterwhite said. The officer who fired his weapon was placed on administrative duty, which is standard procedure after an officer fires his service weapon. Satterwhite said the officers may have been in less danger if the 9-1-1 callers had given dispatchers more information about the situation at the complex. "We always need as much information as the public has and can share for us," Satterwhite said. "We want to prepare our officers. They're already going into a dangerous situation every day, with these types of calls. The more information we have the better prepared we can be."