Two Australians, a teacher and a youth worker, are dead after being struck by lightning at a waterfall in north-east Thailand while touring with students from a Perth school.

Winthrop Baptist College social studies teacher Gregory Crombie, 41, and 19-year-old Thomas McGuinness, died after the group was caught in an electrical storm in Khon Kaen province late on Saturday.

Three Thai nationals also died after being struck by lightning, but the college says they were not with the Winthrop college student group sightseeing at the waterfall.

Mr Crombie's sister-in-law Thongsom Paggangwaesang told local media the group had been swimming at the waterfall when the storm hit at Mukdahan, 642km from Bangkok.

She said two bolts of lightning struck and several people collapsed.

"Before the accident, I saw a tourist talking on a mobile phone near the group," Thongsom said, who had acted as a guide for the Australian group.

Some of the students were rushed to the local hospital and then transferred to the main regional township of Ubon Ratchathani, 135km south-west of Mukdahan.

"It's tragic that Greg and Thomas have died, but obviously there are other people hurting as well, not just the college," Winthrop board chairman Rod White said.

"The only heart we take from that is that the college is a close-knit community. They will draw together and take some strength from each other.

"Also, we know that both Greg and Thomas were doing things that they were passionate about, and in a very small way I guess that sort of helps that ... they were out doing what they felt they'd been called to do."

Mr McGuinness, a friend of Mr Crombie from Perth, was not employed by the school but had joined the 14 Winthrop college students and teachers on a cultural exchange visit to Thailand.

Mr Crombie was married with four children, ABC Television said in a report from Thailand.

Winthrop principal Peter Burton and a counsellor had arrived in Thailand and met with DFAT staff in Bangkok, and they were now heading up to the Khon Kaen province to meet up with the distressed students.

Students injured in the storm had rejoined the group after medical observation.

Mr White also said students had been able to speak with their parents in Australia.

Baptist churchgoers at the college campus at Murdoch, a southern Perth suburb, on Sunday morning offered prayers for the dead and injured.

Mr White said the Baptist community was offering prayers for all the deceased, not just the Australians involved.

People attending a Baptist sports camp in the south of the state would gather on Sunday night to pray, he said.

"People have gone away for a long weekend so even trying to bring the community together in one place is not ... logistically possibly just yet," Mr White said.

"So as quickly as we can people are praying, and I guess the one thankful thing is that there is a lot of support.

"We obviously just need to work quickly to get the group home ... and assist the families affected."

Australian Embassy staff in Bangkok have been assisting the group, a Department of Foreign Affairs and Trade spokesman said.

Federal Opposition leader Malcolm Turnbull also offered his condolences to the families.

"All of us recognise Australians abroad when they're injured are worthy of our support and our care," Mr Turnbull said.

Bloody hel_l.

Dived on this to add a joke until I read it; jeez what a sad tale.....................Quite shaken by how tenuous our hold on life is proved to be yet again.

Did exactly the same.

Surely it's unusual for this to happen to so many people at once?

A real tradegy and my condolenced to the bereaved.

Tragic.

Only two things in life really scare me - Having a gun pointed at me buy a metally un-stable person & lightning.

Both highly un-predictable.

So sad.

I too was expecring a joke thread, this is so tragic and yes, it does prove how tenuous our lives can be.

My sincere condolences to family and friends.

I never took lightening seriously until I started playing golf with Thais. They take off all their jewelry and turn off their phones when there's a chance of lightening. I have to do the same otherwise they won't come near me.

Unfortunately it's not something which visitors would easily become aware of.

Perhaps the Australian authorities can be persuaded to add a sentence or two in their travel information about the danger of tropical thunderstorms. They claim lives every year in Thailand.

My apology to people who thought I was posting something to amuse - I was saddened to read this but thought it better here in Bedlam than posting it in General where the "jokes" would have come fast and hard

CB

My apology to people who thought I was posting something to amuse - I was saddened to read this but thought it better here in Bedlam than posting it in General where the "jokes" would have come fast and hard

CB

I am afraid that is a sad indictment of General, but so true.

May they Rest in Peace and their families find succour at this tragedy.

Moss