Twelve people were killed when a passenger bus and a sand-laden truck collided head-on on the Bonpara-Pabna highway in Natore early on Tuesday, and police say the bus had been running without a valid fitness certificate since May.

The crash happened at about 4:15am at Sarkarpur in Baraigram upazila, near the Bonpara police investigation centre. Nine people died at the scene and three more died later while being treated, taking the toll to 12, according to accounts from The Daily Star and Bangla Tribune. At least 25 people were injured, Bangla Tribune reported, while The Daily Star put the number receiving treatment in Natore and Rajshahi hospitals at 30 or more.

The bus belonged to RP Special Paribahan and was carrying about 40 passengers from Barguna to Chapainawabganj, a journey of more than 500 kilometres that it began around 6:00pm and was due to finish around 6:00am. The truck was taking sand from Panchagarh to Jhenaidah. The two vehicles met at Sarkarpur before dawn.

The dead included the truck's driver and the bus's supervisor. Police said the supervisor was at the wheel when the crash happened; passengers alleged that the driver had been asleep, a claim the owner rejected. A child was also among those killed. The injured were taken to hospitals in Natore, Baraigram and Rajshahi, and the bodies were handed to families after identification.

Police filed a case at Baraigram police station on Tuesday night under the Road Transport Act, naming the drivers of both vehicles as accused but without recording their names. The case was filed by Sub-Inspector Akbar Hossain of Bonpara Highway Police after no relative of a dead or injured passenger came forward to lodge a complaint, and it will be investigated by highway police. Officers said the drivers would be identified and brought under the law.

The condition of the bus is now central to the investigation. Md Alamgir Hossain, officer-in-charge of Bonpara Highway Police Station, said the vehicle's fitness certificate expired in May and that the matter had been passed to the district administration's inquiry committee. "We are investigating how it was allowed to run on this long route for so long without proper certification," he said.

The owner, Md Mintu Ali, said he bought the Ashok Leyland bus about a year ago and first rented it out for tours and picnics. After obtaining a route permit, he began operating it on the Barguna-Chapainawabganj route about four months ago. He said he had applied to the Bangladesh Road Transport Authority to update the vehicle's documents but kept it on the road because of delays in the process. The Daily Star said it could not reach BRTA officials to verify that account.

Mintu denied that the driver had fallen asleep, saying two drivers were aboard and that the crash was the result of a momentary lapse in concentration. The seven-member inquiry committee, headed by Natore Additional District Magistrate Md Abul Hayat, visited the site on Wednesday. Hayat confirmed that the bus had been operating without fitness clearance for five months and said the panel would check all papers, official documents and safety requirements before drawing conclusions.

"Our preliminary assessment suggests the driver may have been drowsy, leading to a loss of control," Hayat said. "We will reveal all findings regarding the cause of the accident after the final investigation concludes." He said the committee would also examine the dispute over who was actually driving at the time of the collision.

The crash has also brought promises of help for the families. Whip Ruhul Kuddus Talukder Dulu, the MP for Natore Sadar, visited the scene with fellow MP Abdul Aziz, Deputy Commissioner Sumoni Akter and Superintendent of Police Shariful Haque. Dulu said the government would give Tk 1 lakh to each bereaved family on behalf of the prime minister, and that work would be taken up to widen the Bonpara-Pabna highway to reduce the risk of such collisions.

Several questions remain unanswered. Police have not said whether anyone has been arrested, and the inquiry committee has not set a date for its report. It is still unclear who was driving the bus, whether the BRTA took any action over the expired certificate, and whether the case will proceed against named individuals. Transport specialists have long warned that a single driver on a 500-kilometre overnight route is a safety risk, and that informal handovers between drivers on long-haul services make crashes more likely.

The Bonpara-Pabna stretch is part of the Dhaka-Rajshahi highway, one of the country's busiest long-distance corridors. The case has renewed attention on how vehicles with out-of-date papers can keep running, a question the inquiry committee says it will address in its findings.