(CNN) -- Four people, including a police officer and the suspected gunman, were shot Thursday near Justin, Texas, authorities said.

The suspect was pronounced dead on arrival at a local hospital, Jody Gonzalez, chief of emergency services for Denton County, Texas, told reporters. It was not immediately clear whether the suspect shot himself or was shot by the officer.

The officer was in stable condition, Gonzalez said, and he was alert and talking.

Authorities did not release the names of those involved. The suspect was a 29-year-old man, said Tom Reedy, spokesman for the Denton County Sheriff's Office.

The incident began at 8:43 a.m. (9:43 a.m. ET), when authorities received a call of a suicidal suspect, Gonzalez said. As the officer was responding, a second call came in reporting that two people had been shot.

As the officer arrived, he was "met with gunfire" in the front yard of the home, Gonzalez said. The officer was able to call in after being shot, Reedy said. The suicidal suspect is the suspected gunman.

"This is a one-family situation that we're dealing with," Gonzalez said. The suspect and the two initial victims were all family members, he said.

The initial two victims were flown to a hospital, while the suspect was taken to a hospital by ambulance and later pronounced dead.

The suspect was armed with a shotgun, Gonzalez said.

Justin is about 45 miles northwest of Dallas. Gonzalez said it is a small town, where "everybody knows who everybody is. It's a tight community. This will have a major effect."

CNN's Vivian Kuo contributed to this report.