PORT ST. JOHN, FL — In the middle of the night, Tonya Thomas’ neighbors awoke to the sound of a gunshot and moments later heard a knock on their door.

Three of Thomas‘ four children were outside, including one who appeared to have been shot. Before the neighbors could offer help, Thomas came out of her house and called the children back home.

They complied. The neighbors dialed 911 after hearing more gunshots.

Brevard County Sheriff’s deputies found Thomas, 33, dead of an apparent self-inflicted wound and three of her children — Jaxs Johnson, 15; Jazzlyn Johnson, 13; and Joel Johnson, 12 — were fatally shot inside the house. A fourth child, Pebbles Johnson, 17, was found shot to death in the front yard of a neighbor’s house.

Investigators said they didn’t know a motive for the shooting and weren’t sure why the children followed their mother’s orders to return to the house.

“From what the neighbors said, she was very calm. She walked out and called them back. They turned around and walked back to the house,” said sheriff’s spokesman Lt. Tod Goodyear.

Another neighbor told deputies Thomas sent a text message in the middle of the night saying she wanted to be cremated with her children.

“He didn’t see the text until he woke up this morning,” Goodyear said.

The shooting happened in Port St. John, about 15 miles west of Cape Canaveral in an area known as the “Space Coast” because it is the home of NASA’s Kennedy Space Center, the location of numerous shuttle launches.