At least 13 people were charred to death and 70 injured in a pile-up triggered by dense fog on the Delhi-Agra Expressway near Mathura early on Tuesday.

Eight buses and as many smaller vehicles, including three cars, ploughed into each other and caught fire.

Sources said the crash occurred when visibility had sharply dropped because of the thick fog that blanketed the area. The vehicles collided in quick succession, sparking a massive blaze that gave passengers little time to escape.

“The massive pile-up was primarily attributed to the extremely low visibility caused by the thick fog. The impact was so severe that most of the vehicles caught fire almost instantly, trapping passengers inside and triggering panic at the scene. All 13 died of burns,” said a police officer.

He said eyewitnesses described scenes of chaos as flames spread rapidly from one vehicle to another. Screams for help rang out as passengers attempted to escape. Visuals from the site showed charred remains of the buses.

Two of the deceased were identified as Akhilendra Pratap Yadav, 44, a resident of Allahabad, and Rampal, 75, from Maharajganj district. “The identification process of the rest of the deceased is still on,” the officer said.

Fire tenders, police teams and ambulances rushed to the scene soon after the crash.

Firefighters battled the blaze while rescue teams pulled out survivors and shifted the injured to hospitals in Mathura and neighbouring districts for treatment.

Traffic on the affected stretch of the expressway was halted for hours following the accident. An inquiry has been initiated to ascertain the sequence of events leading tothe crash.

The district magistrate of Mathura, Chandra Prakash Singh, said 13 people were killed in a “very unfortunate way”.

“The accident involved eight buses, one tempo traveller and small vehicles. All the buses, including a state-run bus, were gutted. Two smaller vehicles also got charred. Additionally, six-seven vehicles were damaged. Around 70 people were injured,” he said.

“We have also been instructed to curb vehicle speeds and reckless driving. Vehicles should be allowed to pass in a controlled manner until the weather conditions improve,” he added.

Prime Minister Narendra Modi and Uttar Pardesh chief minister Yogi Adityanath have announced financial assistance for the victims.

On Monday, four people, including two police officers, were killed and 20 injured as the season’s first dense fog led to a collision involving around 20 vehicles on Mumbai-Delhi Express near Haryana’s Nuh.

Modi said on Tuesday: “The loss of lives due to a mishap on the Yamuna Expressway in Mathura, Uttar Pradesh, is extremely painful. My thoughts are with those who have lost their loved ones. I pray for the speedy recovery of those injured.”