México state authorities confirmed that a bus accident on the Capulín-Chalma highway early Sunday morning resulted in the death of 18 passengers, with 27 others reported injured.

The news agency Aristegui Noticias reported that the bus driver lost control after two tires blew out, causing the bus to flip over. Photos from the crash site clearly show the bus on its side and two tires missing.

Although México state authorities were still investigating the cause of the accident, the newspaper La Jornada reported on Monday that the bus had been speeding, adding that there were visible skid marks extending about 50 meters from the scene of the accident.

The passengers were from the city of San Luis de la Paz in the northeastern part of the state of Guanajuato. The bus was reportedly en route to the Sanctuary of Chalma, the second-most visited religious shrine in Mexico.

The sanctuary houses a Black Christ figure that is venerated year-round because of the many miracles attributed to it. During Easter Week last month, local authorities said more than 30,000 pilgrims visited the sanctuary.

Paramedics and emergency personnel from the México state municipalities of Tenancingo, Zumpahuacán, Tenango del Valle and Toluca arrived to give attention to the victims. Several of the badly injured victims were transported to hospital by helicopter.

The Red Cross of Toluca announced on social media that it had sent two ambulances to the crash site, and posted information on which hospital each victim had been sent to.

Civil Protection authorities in San Luis de la Paz were coordinating with México state officials to keep the victims’ families informed.

Fourteen people were pronounced dead at the scene and another four died at area hospitals. The 27 survivors were being treated at hospitals in Toluca, Metepec, Tenancingo and Malinalco.

A bulletin issued by the state police said the accident occurred near the town of El Guarda de Guerrero which is just outside the city limits of Santa Cruz Tezontepec, about 10 kilomters north of Malinalco and 24 kilometers (15 miles) from Chalma.

With reports from Aristegui Noticias and Infobae