At least 40 people were killed and eight others injured after an overcrowded passenger bus veered off a highway and plunged into a rocky ravine in southwestern Pakistan early Friday, authorities said. The accident is among the country's deadliest road crashes in recent years.

According to the Medical Emergency Response Centre (MERC), rescue teams recovered 40 bodies from the accident site, while the injured were rushed to the Trauma Centre in Zhob for medical treatment. Several of the injured are reported to be in critical condition.

A massive rescue operation was launched immediately after the crash. Emergency authorities deployed six ambulances, 12 emergency medical technicians (EMTs) and 10 light transport vehicles to the remote accident site to assist in rescue and recovery efforts.

District officials, local rescue agencies and ambulance services coordinated the operation, while emergency personnel from the neighbouring Khyber Pakhtunkhwa province also joined the rescue mission due to the scale of the tragedy.

Sherani Deputy Commissioner Hazrat Wali Kakar said rescue workers spent several hours retrieving victims from the deep ravine and evacuating the injured. The difficult terrain slowed rescue operations, requiring coordinated efforts from multiple emergency teams.

Preliminary information indicates that the bus had initially departed from Quetta carrying around 36 passengers. However, officials said the vehicle later became overcrowded after picking up additional passengers from another bus that had reportedly broken down along the route.

Authorities have not yet confirmed the exact cause of the accident. Investigators are examining whether overloading, speeding, driver error or mechanical failure contributed to the crash. A detailed probe has been ordered, officials said.

Road accidents remain a major safety concern in Pakistan, particularly on mountainous highways where poor road conditions, overloaded vehicles and inadequate enforcement of traffic regulations often increase the risk of fatal crashes. Several serious bus accidents have been reported across the country in recent years, prompting repeated calls for stricter road safety measures.

The latest tragedy has once again highlighted concerns over passenger safety and enforcement of transport regulations. Officials said further details will emerge as the investigation progresses.