July 17 (UPI) — At least 21 people were killed and dozens were injured after a bus taking students on a school study trip crashed in Uganda, 180 miles northeast of the capital, Kampala.

Local officials said 20 of the dead were students and that pupils and staff were among those injured in the incident on Thursday evening. They said early indications were that the crash occurred after the driver lost control of the vehicle due to a mechanical fault in an area known for frequent crashes.

Police said the bus carrying students and staff from King David Junior School in Kampala was traveling on the edge of Mount Elgon National Park when it left the road, hit a boulder and overturned.

In an online update from the scene, Local Government Minister Balaam Ateenyi Barugahara said the injured were taken to three area hospitals and medical centers and confirmed that the school’s founder and director, Tadeo Ssekade, was killed in the accident.

“We found nine children in critical condition at Mbale Regional Referral Hospital, 16 children receiving treatment at Kaserem Health Centre, three children at Bulambuli Health Centre IV, and the rest at Kapchorwa Hospital,” he said.

The bus was owned by the school.

The Education Department announced an immediate ban on all school trips pending an investigation into the tragedy.

“As an immediate precautionary measure, we must do something about the safety of our children,” said Education Minister John Chrysostom Muyingo.

The group was on their way back to Kampala after a trip to the tourist region, including the 300-foot Sipi Falls on the slopes of Mount Elgon, an extinct volcano.

Uganda has a poor road safety record with thousands of people killed and seriously injured, mostly due to speeding and poorly maintained vehicles and roads.

School transport was already under scrutiny following several serious crashes in the past few weeks.

In October, 46 people were killed and many injured after two buses overtaking in the middle of the night collided, triggering a huge pile-up on the main Kampala-Gulu Highway about 125 miles north of Kampala.