At least 26 people have been killed and more than 71 others injured in an explosion that hit an area near a church in the northern Egyptian city of Tanta, sources say.

State television confirmed the explosion on Sunday but the cause of the blast is yet unknown.

Provincial governor Ahmad Deif told state television that the explosion occurred inside the church. “Either a bomb was planted or someone blew himself up,” Deif said.

The sources added that there was a second blast near the city’s police academy.

Egypt has been facing violence due to terrorist attacks across the country in the past years. The Takfiri Velayat Sinai terrorist group has claimed responsibility for most of the attacks.

The group, previously known as Ansar Bait al-Maqdis, was founded in 2011, and in mid-2013, it began a campaign of deadly attacks against Egyptian security forces.

Militants have been taking advantage of the turmoil caused in Egypt after the country’s democratically-elected president, Mohamed Morsi, was ousted by the military in July 2013.

Velayat Sinai has killed hundreds of soldiers and police officers, particularly in the Sinai Peninsula, since then. In November 2014, it pledged allegiance to the Daesh terrorist group, which is mainly active in Syria and Iraq, and renamed itself again as Daesh-Velayat Sinai Province.