For the last decade, the two parts of the Palestinian territories, the West Bank and the Gaza Strip, were ruled by mutually antagonistic groups that only recently agreed to bury their differences.
Hamdallah was not hurt and a short time later attended the inauguration of a sewage plant.
Iyad al-Buzom, Gaza's interior ministry spokesman, said the act of placing blame "has a political dimension".
Hamdallah was traveling with Palestinian intelligence chief Majid Faraj to the opening of a waste treatment facility, reports said.
In his return, Hamdallah assured that all evidence points to the fact that the attack on his convoy had been well prepared, with the bomb that exploded buried in the road through which he entered Gaza this morning.
He said the attack underscored the need for the Palestinians to unify under a single authority.
Immediately after the attack, he said he would go ahead with the visit and it would "not deter from seeking to end the bitter split".
The US is set to discuss the dire humanitarian situation in Gaza during a White House meeting later on Tuesday.
The long, lopsided history of Woods and Els
One person with knowledge of the decision said Woods reached out to the PGA Tour about his interest in being the next captain. The two players infamously went head-to-head in a play-off in the 2003 Presidents Cup after the match ended in a 17-17 tie.
The United Nations Mideast envoy also condemned the attack.
"This attack targets the efforts of President Mahmoud Abbas to achieve unity and end all internal divisions", the office added in a statement, "Whoever is behind the explosions is directly serving Israel's interests, this is a serious and unsafe development and a desperate attempt to foil unity efforts".
In the West Bank, Abbas blamed Hamas for the blast.
The blast occurred on Tuesday after Hamdallah and his convoy passed through the Beit Hanoun checkpoint in northern Gaza.
The World Bank, European Union and other European governments have paid almost $75 million in funding.
Hamas and the authority, led by President Mahmoud Abbas, are still divided over how to share administrative power in the Gaza Strip under an Egyptian-brokered unity deal.