SALISBURY PLAIN, England (AP) _ About 200 people stormed the prehistoric Stonehenge monument in England today, clashing with police as they tried to observe the summer solstice.

The crowds pushed through the perimeter fence surrounding the stones and occupied the site, which was opened to a limited number of druids for a ceremony to watch the sun rise on the year's longest day.

Many of the invaders were thrown out by police and 16 were arrested, but others remained at the site in defiance of riot police and mounted officers, Wiltshire police spokeswoman Elizabeth Marginson said.

The druid celebration _ for which 150 people had been given permission to enter the site _ had to be canceled.

Revelers have been banned from holding solstice ceremonies at the 5,000-year-old Stonehenge site since the 1980s after clashes with police.

But last year, for the first time in a decade, English Heritage, which owns the site, allowed 100 people to gather within the encircling rocks at dawn to celebrate the summer solstice as part of a step toward admitting larger crowds.