Dallas police are investigating three fatal shootings that occurred within a 12-hour span beginning Saturday evening.

As of Sunday afternoon, no arrests had been made in any of the shootings, which occurred in South Dallas, northeast Dallas and east Oak Cliff.

A 26-year-old man was shot multiple times at a house in the 4300 block of Jamaica Street in South Dallas about 7:40 p.m., police said. Shundarek Smith, of Balch Springs, apparently called a friend after he was shot, police said.

The friend drove to the area, picked up Mr. Smith and then flagged down officers in the 4900 block of Hatcher Street, police said. An ambulance took Mr. Smith to Baylor University Medical Center at Dallas, where he was pronounced dead, police said.

A few hours later, police said, a 34-year-old man was shot and killed in a robbery at an apartment complex in the 6500 block of Melody Lane in northeast Dallas.

Officers said the slain man was driving a truck, with two other men inside, that pulled into a parking space at the complex about 10:40 p.m.. Two other men ran up to the vehicle, opened the driver and passenger side doors and robbed the three inside at gunpoint, shooting two of them.

The driver died at the scene, police said. The passenger in the front seat was shot as he tried to run away and was taken to Baylor hospital in serious condition, police said. The other passenger was not injured.

The name of the deceased was being withheld Sunday because his family had not yet been notified.

Homicide detectives were called out again early Sunday morning after a fatal shooting in the 2900 block of Seevers Avenue in east Oak Cliff, police said. About 6:30 a.m., a witness knocked on the door of a nearby house and reported the shooting.

Officers found Alfredo Hernandez Goana, 30, shot multiple times inside what police believe is a pool hall and bootleg house. Mr. Goana, who is believed to be a Mexican citizen, was pronounced dead at the scene, police said.

Anyone with information on any of the shootings can call the Dallas police homicide unit at 214-671-3661 or e-mail homicide@dpd.dallascityhall.com.