People sit in a car as a member of Palestinian Hamas security forces checks an identity card at a checkpoint in Khan Younis in the southern Gaza Strip, Aug. 28, 2019. Photo: Reuters / Ibraheem Abu Mustafa.

Explosions hit two police checkpoints in the Gaza Strip on Tuesday, killing three officers and wounding several other Palestinians, the Hamas-run Interior Ministry said, declaring a state of emergency after the blasts.

Such attacks on Hamas, which has the most powerful armed apparatus in the enclave, were rare.

Interior Ministry spokesman, Eyad Al-Bozom, said security forces were making progress in their pursuit of those behind the explosions, but he did not disclose further details.

“The sinful hands that carried out this crime will not escape punishment,” said Bozom.

A spokesman for the Israeli military said he knew of no involvement by Israel in the back-to-back incidents in Gaza city at a time of simmering cross-border confrontations with Hamas, the Palestinian enclave’s ruling Islamists.

The first blast destroyed a motorcycle as it passed a police checkpoint, witnesses said. Two police officers were killed and a third Palestinian wounded. It was not immediately clear if the riders were among the casualties.

The second explosion, less than an hour later, killed one officer and wounded several people at a police checkpoint elsewhere in the city, the interior ministry said. The ministry declared a state of emergency throughout Gaza, putting security forces on alert.

Hamas, which took over Gaza in a 2007 civil war with the forces of Palestinian Authority President Mahmoud Abbas, has at times faced internal opposition from more stringent Islamist militants aligned with al Qaeda or Islamic State.