NA KLANG, Thailand (AFP) — Please be a teacher in heaven, and my child please take care of your mother in heaven.

These were the words posted on Facebook by Seksan Srirach, husband of a pregnant teacher who was among at least 37 people shot and stabbed to death in a shooting rampage at a nursery as Thailand mourns the victims on Friday.

"I would like to thank all the support for me and my family. My wife has fulfilled her every duty as a teacher," Srirach also wrote in a poignant tribute on Facebook for his wife Supaporn Pramongmuk.

Weeping, grief-stricken families gathered Friday outside a Thai nursery where an ex-policeman murdered two dozen children in one of the kingdom's worst mass killings.

Around the small low-slung building, where only two days ago scores of preschool children played, officials in white uniforms laid a large floral wreath on behalf of the king.

A line of heartbroken parents placed white roses on the steps of the nursery as the baking sun bore down on them.

Flags on government buildings flew at half-mast in a gesture of mourning.

Overnight, coffins carrying the bodies of the victims arrived at a morgue in Udon Thani, the closest city to the rural district ripped apart by Thursday's three-hour mass shooting.

Armed with a 9mm pistol and a knife, sacked police sergeant Panya Khamrab opened fire on the childcare center in the northeastern Nong Bua Lam Phu province at about 12:30 p.m.

Nanthicha Punchum, acting chief of the nursery, described harrowing scenes as the attacker barged into the building in the rural Na Klang district.

"There were some staff eating lunch outside the nursery and the attacker parked his car and shot four of them dead," she told AFP.

She said the attacker smashed down the door with his leg and then started stabbing the children.