(NBC DFW) --
An ongoing standoff at an Arlington apartment complex is entering its fifth hour Monday morning after one person has been shot and more than two dozen residents have been evacuated.
Several residents at the Silverwood Apartments in the 1100 block of Silverwood Drive called 911 at about 6 a.m. Monday reporting gunfire. When police arrived on the scene, they reported seeing a person lying near a car in the parking lot.
Police believe one armed person is barricaded in an apartment and that he has access to "multiple weapons." Police made contact using a mobile phone, but the person is refusing to come out.
Lt. Christopher Cook, with the Arlington Police Department, said officers have identified one injured person but that person's condition was not clear. No other injuries were confirmed. Investigators have also said they know who the gunman is, but they have not released any identifying information.
Arlington police have requested SWAT assistance from the Grand Prairie Police Department. Law enforcement personnel have surrounded the complex and are attempting to negotiate with the person.
Meanwhile, about 25 residents of the complex were evacuated by Arlington police. Officials with the Arlington Independent School District said some of the residents inside the building were school-aged children.
Avenue J is closed between state Highway 360 and Corporate Drive due to the incident, according to NBC 5's Keaton Fox, who was at the scene.
Resident Treg Hill told NBC 5 he heard four gunshots from the complex initially, but has heard additional shots fired at different intervals as police have arrived on scene. Hill lives in the Oak Forest Apartment next door to the Silverwood Apartments.
Hill said officers with automatic weapons arrived at about 6:45 a.m. and that he has heard officers using a bullhorn to attempt to communicate with the suspected shooter.
"You could hear the first series of shots, it was about five shots in the morning. Really early this morning I heard a little bit of arguing and screaming. You had another series of shots, then it was really quiet for a long time," says neighbor Omar Richards. "A little bit before 5 o'clock some pretty heavy back-and-forth shooting started, and probably about 3 series of 5 shots every time."
Jeff Bidwell's family, including his 3-year-old grandson had to crawl out of a window to escape.
"Heard a lot of shots over across from us. The apartment faces east and west and my apartment fortunately faces north and south," said Bidwell. Bidwell heard more gunfire once he was down the street.
"We got over there by the fire truck and stayed over there out of the way." Bidwell said.
NBC 5 has crews on scene to gather additional details. As this is a developing story, information may change as we gather more details.