TIONE, Italy (AP) _ Seven schoolchildren were killed Wednesday by an avalanche set off by a sudden and violent thunderstorm. Seven others were trapped for about four hours beneath snow, mud and stones before being rescued.

Police said the seven trapped children and two adult companions were hurt, but hospital doctors in the alpine village 81 miles northeast of Milan later said all were out of danger.

The storm that sent a wall of snow and mud crashing down a mountain also spawned a tornado that injured six people and damaged campgrounds and buildings on the northern shore of Lake Garda, southwest of the avalanche site.

One traffic death also was blamed on the storm.

The children were among 24 students, aged 12 to 15, from Our Lady of Lourdes parish in Piacenza who were on a two-day alpine hike. Ten children walking ahead of the others escaped harm.

A police spokesman said the children hiked to a telephone to call for help.

''It was a terrible scene. The rescue workers were white with snow, like winter,'' said Giuseppe Simonetti, pilot of one of the rescue helicopters. ''I had the blades of the rotor ... (inches) from the rocks to load the bodies. Then down to the valley and back up again to load more.''

He said the avalanche happened at a place not generally considered dangerous, a location crossed every summer by thousands of tourists.

Piacenza Mayor Franco Benaglia declared Thursday a day of mourning in the city of 105,000 people, 40 miles southeast of Milan.

Italian news reports said 38 children from Piacenza were taking part in a 10-day summer excursion, but that only 24 were on the hike.