An Auckland woman whose 16-year-old son wasn't far from where the bomb went off in Bangkok she said she has now heard from him and he's safe.

Tere Parsons' son was at a Muay Thai Kickboxing championship in Bangkok with a team of 25 Kiwi athletes.

The team was heading back to their hotel when the bomb went off.

Ms Parsons said she tried to remain calm when she found out about the explosion, but wasn't able to get hold of her son Haamiora until late yesterday.

She said her daughter was the one who found out he was safe.

Meanwhile a second explosion has gone off in Bangkok.

Unlike Monday night's incident, no one was killed.

Witnesses say a pipe bomb was thrown off a bridge and detonated when it hit a pillar.

Police continue to search for a man they believe is responsible for the first blast that killed at least 20 people and injured 140 others.