One person has been killed and four others wounded by a bomb that went off outside a Gaza City cafe.
The explosion, in the early hours of Friday morning, was followed by a second blast near a Hamas politician's house.
The cafe, which was badly damaged, has been targeted in the past, emergency services and police said.
Witnesses blamed "gunmen" for the attacks on Friday, suggesting the involvement of a Palestinian faction.
Internet cafes, shops that sell music deemed unsuitable and Christian institutions have been attacked in the Gaza Strip in the past.
Islam Shahwan, a police spokesman, said the second bomb exploded near the home of Marwan Abu Ras, the Hamas official responsible for publishing religious edicts, in Gaza.
No one was reportedly hurt.
Shahwan said two members of the Fatah movement of Mahmud Abbas, the Palestinian president, had been arrested in connection with the second blast, and that one of them had placed the bomb.