KATHMANDU, Nepal (AP) — A helicopter carrying foreign tourists went missing Tuesday in the Mount Everest area of Nepal and contact was lost with the aircraft.

The helicopter was returning to the capital Kathmandu on Tuesday morning after bringing the five tourists on a sightseeing trip to the world’s highest peak.

A search effort was underway involving another helicopter in the skies and police and soldiers on the ground. Much of the mountainous area is only accessible on foot with no roads.

Airport official Sagar Kadel said weather conditions had caused changes to be made to the helicopter's planned flight route.

It is common for flights to be delayed and routes changed during the monsoon season amid heavy rains.

The tourist and mountaineering season ended in May with the onset of the rainy season and tourist flights to the mountains are less common this time of year as visibility is poor and weather conditions become unpredictable.