On a leafy cul-de-sac in a gated Texas community, a man walked inside his stepfather's home with a briefcase. A teenage boy at the house didn't recognize him but could tell he was angry. He took his young siblings outside, and moments later heard gunfire.

There were no signs of an argument before the man, identified by police Thursday as 69-year-old Joseph Ray McDonald, took two guns from the briefcase and fatally shot his 88-year-old stepfather, another man and the children's mother. He then turned the weapon on himself.

The children, who were playing in the backyard, raced to a neighbor's house after hearing the shootings — and the eldest seeing his mother being shot — late Wednesday in San Antonio's affluent north side, according to police records.

A day later, police still didn't have a motive.

"We're unsure why the suspect chose to commit three murders and then take his life," San Antonio police Sgt. Chris Benavides said.

Killed were McDonald's stepfather, Arthur DeBuan; Jeffery Monroe, 41; and Heather Monroe, 40, who was DeBaun's granddaughter and the mother of the three children, ages 8, 10 and 14. The Monroe family was planning to move into DeBuan's house, according to police.

The children were placed with family members.

The shootings began just after 8 p.m. Wednesday. After McDonald arrived, the 14-year-old saw that he looked angry and took his brother and sister out back to play with the dogs. The teenager told police he didn't recognize the man, according to police affidavits.

"He ran to a window that looks into a living room and saw (McDonald) standing over (his mother) and was firing his pistol at his mom," the affidavit stated.

The teenager "then told his brother and sister to run," an affidavit said.

The three children escaped out of a side gate and ran to neighbors for help. The teenager told police he heard one more shot as they fled — perhaps McDonald shooting himself.

The shooting happened behind the gated entry of a small neighborhood with just four short streets. An American flag hung outside the one-story brick house, which is valued at more than $300,000, according to Bexar County tax records.

Dwight Dunlap, an attorney who said he represented some of the family, declined comment while standing outside the home.

There was no sign of forced entry, and Benavides said there were no signs that an altercation took place before the shooting began. McDonald brought the guns into the house in a briefcase, Benavides said.

Eugene Goldman, who lives a few houses down, said he saw removal vans come and go from DeBaun's house in the days leading up to the shooting. He figured it was Monroe moving in.

Goldman said he walked outside to exercise shortly after 8 p.m. when a neighbor asked if he had heard gunfire. A rush of police cars and ambulances packed the quiet cul-de-sac soon after the shooting was reported, after the kids had ran to safety.

The shootings shocked residents who believed their neighborhood was safe.

"This is why we live in a gated community," Goldman said.