At least 18 school children and teachers have died in a flash flood near Jordan's Dead Sea, which happened while they were on an outing.

34 people were rescued in an operation involving helicopters and army troops, police chief Brigadier General Farid al Sharaa told state television. Some of those rescued are in a serious condition.

Many of those killed were children under 14. A number of families picnicking in the popular destination were also among the dead and injured, rescuers said.

Hundreds of families and relatives converged on Shounah hospital a few kilometers from the resort area. Relatives sobbed and searched for missing children, a witness said.

King Abdullah cancelled a trip to Bahrain to follow the rescue operations, state media said.

Israel sent search-and-rescue helicopters to assist, an Israeli military statement said, adding the team dispatched at Amman's request was operating on the Jordanian side of the Dead Sea.

Civil defence spokesman Captain Iyad al Omar said the number of casualties was expected to rise.

Rescue workers using flashlights were searching the cliffs near the shore of the Dead Sea, where bodies had been found.

A witness said a bus with 37 school children and seven teachers had been on a trip to a resort area when raging floodwaters swept them into a valley.