At least 16 people have been killed and more remain missing after a landslide enveloped a campsite in Malaysia's Selangor state, officials say. Campers were sleeping in their tents when a landslide occurred around 03:00 Friday (19:00 GMT Thursday) at the farm stay in Batang Kali township. More than 90 people - including children - had been camped at the base. Hundreds of rescuers were at the scene on Friday morning wading through mud to try to find survivors. The landslide began up a slope more than 30m (100ft) higher than the campsite, and rolled through an acre of land. Pictures posted online by Malaysia's rescue agencies showed crews of helmeted workers clambering up uneven ground, past uprooted trees and other debris. By Friday afternoon, authorities had rescued more than 60 people but 17 were still missing, they said. One camper Teh Lynn Xuan said she and her mother had survived, but her brother had died and another brother had been taken to hospital with injuries. "We felt the tents becoming unstable and soil was falling around us," she told Malaysian newspaper Berita Harian. "My mother and I managed to crawl out and save ourselves." She had been camping with a big group of more than 40 people. Prime Minister Anwar Ibrahim was due to arrive at the site later on Friday, following visits from several other government ministers. He offered condolences to the victims and prayers for more survivors on his Facebook page. It's unclear what triggered the landslide, which happened in a forested hilly area next to the side of the road in Batang Kali, close to the holidaying Genting Highland region and about 50km (30 miles) north of Kuala Lumpur. Locals reported there had been some light rain, but no heavy downpours or any earthquakes in the lead up to it. On Friday afternoon, authorities also issued an order for the evacuation of all campgrounds on riverbanks and other high-risk areas for the next seven days.