Three congressional Democrats, including Senator John Kerry of Massachusetts, chairman of the Foreign Relations Committee, visited Gaza on Thursday, saying they wanted to see for themselves the destruction caused by Israel’s war last month and assess the area’s needs.

They were the first American government officials to visit this Palestinian coastal strip run by Hamas in more than three years and the first American legislators to come here since 2000, according to a spokeswoman for the American Consulate in Jerusalem.

Mr. Kerry, who is on a tour of the region, entered Gaza after seeing the remains of Palestinian rockets fired at the Israeli city of Sderot. He was accompanied in Sderot by the Israeli foreign minister, Tzipi Livni, who is engaged in coalition negotiations in the wake of elections more than a week ago.

Mr. Kerry said that his visit indicated no change in American policy toward Hamas, which is labeled a terrorist group by the United States, and that he would not be meeting with Hamas leaders.

“Hamas has to change its policies,” Mr. Kerry said while visiting the ruins of the American International School in Gaza, which was destroyed by an Israeli air attack in early January. “There is no change in our policy.”

Separately, two other congressmen visited Gaza — Representative Brian Baird, Democrat of Washington, and Representative Keith Ellison, Democrat of Minnesota. Their trip was arranged independently of Mr. Kerry’s but included similar tours of destroyed areas and meetings with United Nations officials.

Although none of the Americans saw Hamas officials, a senior Hamas leader said he was pleased by their visit.

“This is a very good step reflecting the seriousness of this administration to follow up and get information about what is happening on the ground,” said Ahmed Youssef, the deputy foreign minister in the Hamas government. “We know that we are still on the terrorist list and we know their position about not engaging with Hamas. But we are still happy that they are the ones evaluating the scale of the Israeli crimes and the destruction caused by Israel. By seeing for themselves, they can get a more balanced view than that of the previous administration.”

Mr. Kerry seemed intent on learning what Gaza needed. He spent some time talking with Sharhabeel al-Zaeem, a Gaza lawyer who is on the board of the American school, and asked him what Gaza most needed now.

Mr. Zaeem said the central need was for an opening of the border crossings into Gaza so that the destroyed areas could be rebuilt and the economy restarted following the war and several years of an Israeli-led embargo on Gaza in protest over rule by Hamas, which seeks Israel’s destruction.

Asked whether Gaza had enough food, Mr. Zaeem said it did but that it did not have enough fuel for its cars because Israel was not allowing enough in. He added that Israel contended that its security was threatened by allowing more goods into Gaza, but in his view Israel’s security was even more endangered by the closure of the borders because it bred frustration and radicalism.

Mr. Kerry said Israel had a right to respond to rockets launched by Hamas.

“Your political leadership needs to understand that any nation that has rockets coming into it over many years, threatening its citizens, is going to respond,” he said.

Palestinian militants fired rockets into Israel again on Thursday, the latest volley of more than 50 rockets and mortars shot into the country since the Gaza incursion ended on Jan. 18. The Israelis have responded by carrying out raids on smuggling tunnels in southern Gaza and killing and wounding some militants in targeted strikes.

Efforts to reach a new cease-fire between Hamas and Israel ran into a major roadblock on Wednesday when the Israeli security cabinet voted to make such a truce contingent on the return of a kidnapped soldier, Cpl. Gilad Shalit.

Hamas wants the commercial crossings opened and says nothing can happen until they are. Israel says nothing can happen before Corporal Shalit is returned. Egypt has been trying to mediate.