16 Inmates at Large After Escaping Mexican Prison Through Tunnel

A Federal Police patrol car escorts vehicles with civilians along the gang-infested Matamoros-Ciudad Victoria highway, Tamaulipas State, Mexico, in the border with the United States, in this file photo from December 16, 2015. (Credit: Ronaldo Schemidt/AFP/Getty Images)

Sixteen of 29 inmates are still on the run after they made an audacious escape by tunneling underneath a Mexican prison wall, authorities said.

The inmates escaped Thursday from a prison in Ciudad Victoria, Tamaulipas state secretariat of security said Saturday

Following the escape, security officials destroyed unauthorized shelters constructed by inmates on prison grounds and searched cells.

In reaction to those efforts, a riot broke out in the prison Friday night. Three inmates were stabbed to death and one was injured, officials said.

The inmates set debris on fire during the riot, but the flames were put out within an hour.

The tunnel was sealed with concrete Saturday.