Gaza - An explosion struck the convoy of the Palestinian prime minister on Tuesday as he was making a rare visit to Gaza, in what his Fatah party called an assassination attempt it blamed on Gaza militants.

The blast further complicated what already is a troubled reconciliation process between Gaza’s ruling Hamas militant group and the internationally backed Palestinian Authority in the West Bank. It also cast a cloud over a meeting later Tuesday at the White House, where international representatives were to discuss economic development and the dire humanitarian situation in Gaza.

The explosion went off shortly after the convoy entered Gaza through the Erez crossing with Israel. Palestinian Prime Minister Rami Hamdallah was unharmed and went on to inaugurate a long-awaited sewage plant project in the northern part of the strip.

There was no immediate claim of responsibility. Some officials in the Fatah movement quickly blamed rival Hamas for a “cowardly attack,” while others said it was too early to say.

Witnesses said the bomb was planted under an electric pole on Gaza’s main north-south road and went off shortly after Hamdallah’s 20-vehicle convoy had entered through the Israeli-controlled crossing.

“I could not see anything because smoke and dust filled the air. When the smoke cleared, the explosion was followed by heavy gunfire, apparently from police securing the convoy. When the dust cleared, I saw people running everywhere, and police were running around,” said a witness who declined to be identified because of security concerns.

Two vehicles were badly damaged and could not continue while at least four others were damaged, with windows or sunroofs blown out. One had signs of blood on the door. At least two bodyguards were lightly wounded.

Hamdallah, who is based in the West Bank, arrived in Hamas-run Gaza to inaugurate the internationally funded sewage plant. He delivered a speech, and immediately left without sticking around for the ribbon-cutting ceremony.

“This will not deter from seeking to end the bitter split. We will still come to Gaza,” he said.

Hamas condemned the explosion, calling it a crime and an attempt to “hurt efforts to achieve unity and reconciliation.” It promised an “urgent” investigation.