MEXICO CITY (AP) — The death toll in a gruesome fireworks explosion during a religious procession in Mexico rose to 17, after four more people died of their injuries.

Hundreds of mourners gathered Sunday for a mass funeral for the first 13 victims of the blast, which occurred on Friday in Jesus Tepactepec, a village of about 1,000 people 70 miles (112 kilometers) east of Mexico City.

The 13 wooden coffins were carried through the streets of the village to a local gymnasium for a Mass attended by Tlaxcala Bishop Francisco Moreno Barron, and the governor of the central state of Tlaxcala, where the village is located. The bishop noted that fireworks form an important part of traditional religious celebrations in the area, but need improved safeguards.

"I appeal to the conscience of the people of Tlaxcala, to reflect and take measures to guarantee the responsible and orderly use of fireworks," Moreno Barron said, according to a statement by the state government.

The statement said 17 people in total were killed and 80 remain hospitalized in Tlaxcala, the neighboring state of Puebla and Mexico City; about 70 others injured in the blast were treated and released.

The massive blast occurred after a rocket malfunctioned and landed on a truck, igniting the fireworks it carried. Some of the victims may have also been carrying bundles of fireworks.

Residents told local media about finding bits of human remains blown into their yards, trees and patios by the blast.

The victims were marching in an annual procession in honor of Jesus Christ, the patron of Jesus Tepactepec.