UTHAI SAWAN, Thailand — Relatives wailed and collapsed in grief before the small coffins of children Friday after a fired police officer stormed a rural Thai day care center at naptime and massacred dozens of people.

Thailand’s deadliest mass killing left virtually no one untouched in this small community nestled among rice paddies in one of the nation’s poorest regions. Grief also gripped the rest of the country, where flags were lowered to half-staff and schoolchildren said prayers to honor the dead.

At least 24 of the 36 people killed in Thursday’s grisly gun and knife attack were children, mostly preschoolers.

“I cried until I had no more tears coming out of my eyes. They are running through my heart,” said Seksan Sriraj, 28, whose pregnant wife worked at the Young Children’s Development Center in Uthai Sawan. She was due to give birth this month.

“My wife and my child have gone to a peaceful place. I am alive and will have to live. If I can’t go on, my wife and my child will be worried about me, and they won’t be reborn in the next life,” he said.

A stream of people, including Prime Minister Prayuth Chan-ocha, other government representatives and relatives, left flowers Friday at the day care center. By afternoon, bouquets of white roses and carnations lined the wall outside, along with five tiny juice boxes, bags of corn chips and a stuffed animal.

Later, relatives received the bodies at the local Buddhist temple. As the small, white coffins were opened, some screamed, while others fainted and were revived with smelling salts. For a time, the grounds outside the temple were crowded with people overcome by grief.

“It was just too much. I can’t accept this,” said Oy Yodkhao, 51, sitting on a bamboo mat in the oppressive heat as relatives gave her water and gently mopped her brow.

Her 4-year-old grandson, Tawatchai Sriphu, was killed, and she said she worried for the child’s siblings. The family of rice farmers is close, with three generations living under one roof.

Som-Mai Pitfai collapsed when she saw the body of her 3-year-old niece.

“When I looked, I saw she had been slashed in the face with a knife,” the 58-year-old said, holding back tears.

Elsewhere, King Maha Vajiralongkorn and Queen Suthida arrived at a hospital where some of the 10 people who were wounded were being treated.

Police identified the attacker as Panya Kamrap, 34, a former police sergeant fired earlier this year because of a drug charge involving methamphetamine. He had been due to appear in court Friday. An employee told a Thai TV station that Panya’s son had attended the day care but hadn’t been there for about a month.

Panya took his own life after killing his wife and child at home. National police chief Gen. Dumrongsak Kittiprapas told the media Friday that initial investigations found that Panya had argued with his wife early Thursday, and called her mother to come pick her up.

“As of now, the police assume that he became stressed because he was afraid that his wife would leave him. This is the important point, because he still looked normal when he went to the court in the morning,” said Dumrongsak, explaining that the ex-officer may have panicked when he came home from court and found his wife absent.

Panya’s mother told Thai media in interviews that there was tension between him and his wife. The mother also told digital television 3Plus News that her son owed 300,000 baht ($7,990 ) for his car loan and 140,000 baht ($3,730) in additional personal debt, which was another possible cause of stress.

The police chief also said the initial autopsy performed on Panya’s body failed to detect any dangerous drugs, which would mean that he had not taken any in the preceding 72 hours. The finding appeared to cast doubt on theories the attack had been carried out in a methamphetamine-induced rage. A second autopsy was planned.

In an interview with Amarin TV, Satita Boonsom, who worked at the day care center, said staff locked the glass front door to the building after seeing the assailant shoot a child and his father out front. But the gunman shot and kicked his way through it.

The children, mainly preschoolers, had been taking an afternoon nap, and photos taken by first responders showed their tiny bodies still lying on blankets. In some images, slashes to the victims’ faces and gunshots to their heads could be seen.

Satita said she and three other teachers climbed the center’s fence to escape and call police and seek help. By the time she returned, the children were dead. She said one child who was covered by a blanket survived the attack, apparently because the assailant assumed he was dead.

She said the center usually has 70 to 80 children, but there were fewer at the time of the attack because the semester had ended for older children and rain prevented a school bus from operating.

“They wouldn’t have survived,” she said.

Satita added that the attacker’s son hadn’t been to the day care center recently because he was sick.

One of the youngest survivors was a 3-year-old boy who was riding a tricycle close to his mother and grandmother when the assailant began slashing them with the knife. The mother died from her wounds, and the boy and grandmother were being treated at hospitals, according to local media.

Mass shootings are rare but not unheard of in Thailand, which has one of the highest civilian gun ownership rates in Asia, with 15.1 weapons per 100 people compared to only 0.3 in Singapore and 0.25 in Japan. That’s still far lower than the U.S. rate of 120.5 per 100 people, according to a 2017 survey by Australia’s GunPolicy.org nonprofit organization.

Thailand’s previous worst mass killing involved a disgruntled soldier who opened fire in and around a mall in the northeastern city of Nakhon Ratchasima in 2020, killing 29 people and holding off security forces for some 16 hours before eventually being killed by them.

Nearly 60 others were wounded in that attack. Its death toll surpassed that of the previously worst attack on civilians, a 2015 bombing at a shrine in Bangkok that killed 20 people. It was allegedly carried out by human traffickers in retaliation for a crackdown on their network.

Last month, a clerk shot co-workers at Thailand’s Army War College in Bangkok, killing two and wounding another before he was arrested.

Associated Press writers Chalida Ekvitthayavechnukul, Elaine Kurtenbach and Grant Peck in Bangkok and Kim Tong-hyung in Seoul, South Korea, contributed to this report.