A 60-year-old man fatally shot four relatives, including his elderly father and stepmother at a nursing home in the US state of Texas before killing himself, police said.

Police in Robstown, Texas, outside Corpus Christi, responded to reports of an active shooter at a nursing home on Friday, where they found the suspected shooter's father, 85-year-old Ernest Starry, his wife Thelma Montalvo, and the suspected gunman dead, Robstown Police Chief Erasmo Flores said Saturday.

The suspected gunman was identified as Richard Starry, 60. “It was a murder-suicide,” Rodriguez said.

After finding the three people dead at the nursing home, a family member prompted police to search the home of the deceased elderly couple.

There officers found a 14-year-old adopted son and the 41-year-old son of Montalvo dead. Investigators believe they were also killed by Richard Starry, police said.

"At this time the evidence points to a murder-suicide, but the investigation is still premature to determine a motive and we will not speculate," police said in a statement.

“You never think it’s going to happen to your family," said Doris Salazar, whose mom stays at the nursing home. “You think they’re safe.”

There are more than 30,000 gun-related deaths annually in the United States.

Mass shootings at US schools are rising rapidly, killing more people in the last 18 years than in the entire 20th century, according to a study published in April by researchers at Clemson University.

The majority of Americans support stricter gun control laws but have little hope that Congress will pass such measures.