A Pakistani military helicopter on Tuesday rescued two of seven children trapped with their teacher in a cable car dangling over a high ravine, but the air rescue operation was called off as night fell.
Flood lights were installed and a ground-based rescue operation was continuing, a security source said.
The source added that cable crossing experts had been sent to the area and a small dolly carrier was being attached to the cable to rescue the children one by one, more than 12 hours after their cable car snagged.
A cable line snapped at around 7:00 am (0200 GMT) as the students were travelling to school in a remote mountainous area in Battagram, about 200 km (125 miles) north of Islamabad.
Two children have now been rescued, a rescue agency spokesperson and a district official said. No further details were immediately available.
The cable car became stranded half way across a ravine, about 274 metres (900 feet) above ground, and was dangling by a single cable after the other snapped, Shariq Riaz Khattak a rescue official at the site told Reuters.
The rescue mission has been complicated due to gusty winds in the area and the fact the helicopters' rotor blades risk further destabilising the lift, he said.
"Our situation is precarious, for god's sake do something," Gulfaraz, a 20-year-old who is on the cable car, told local television channel Geo News over the phone, appealing to authorities to rescue them as soon as possible.
He said the other students are aged between 10 and 15 and one had fainted due to heat and fear.
The rescue efforts have transfixed the country, with Pakistanis crowded around television sets, as local media showed footage of an emergency worker dangling from a helicopter cable close to the small cabin, with those onboard seen cramped together.
At the scene, crowds of villagers gathered on the vertiginous hillside anxiously watching the operation.
Muzaffar Khan, a district administration official in Battagram, said there were seven students and one teacher aboard, updating from the earlier reported six students and two teachers.