What caused some Hamas members to be arrested?

Palestinian police have arrested six members of the militant Islamic Resistance Movement (Hamas) in connection with a bomb explosion earlier this week at a controversial Jewish housing project, security sources said yesterday. The security sources gave few details on the arrests, saying they started on Tuesday in the villages of Beit Sahour and Taamara near Bethlehem in the southern part of the West Bank. The small bomb exploded on Monday night near the site of the controversial Jewish housing project of Hat Homa in the East Jerusalem district of Jebel Abu Ghneim, but no one was in the area at the time.