(CNN) -- Thirty-two people -- 30 students, a teacher and the bus driver -- were killed and more than 70 others were injured in Pakistan Monday when a bus returning from a school study trip and picnic overturned, officials said.
The students' ages ranged from 10 to 15, according to Zahid Saeed, the top government administration official of Rawalpindi region, where the accident occurred.
The bus had a capacity of 72 persons but more than 100 students and a couple of teachers -- all from a school in Faisalabad in eastern Pakistan -- were aboard, Saeed said. He cited overcrowding, too much speed and brake failures as causes for the wreck. The driver was among the fatalities, Saeed said.
One survivor interviewed by phone on Pakistan's Geo News TV channel identified himself as a 15-year-old ninth-grader.
"Brakes failed, the bus got speed on the slope and overturned," said the student, who gave his name as Sangraiz.
The bus wrecked near Kallar Kahar, a tourist destination about 125 kilometers (about 78 miles) southeast of the Pakistani capital of Islamabad.
Saeed said the students and teachers were heading home after a study trip and picnic in Kallar Kahar.
A surviving student interviewed by Pakistan's Express News said, "All of us were crying when the brakes of the bus failed."