A powerful blast went off in the house of a senior Islamic Jihad operative Friday, killing at least five people and wounding 40, medics and Hamas said.

Witnesses said the three-story home of Ayman Atallah Fayed had completely collapsed, and that six nearby home were also badly damaged. The blast went off Friday evening in Fayed's house in the Bureij refugee camp in central Gaza.

Islamic Jihad said Israel targeted the house in an air strike, but Hamas said the cause of the blast was not clear. The IDF said it had no knowledge of any strike on Bureij.