The United States expressed concern Wednesday about tens of thousands of Palestinians pouring into Egypt from Gaza across a broken barrier that the Israelis had erected at the border for security.

"We are concerned about that situation and frankly I know the Egyptians are as well," State Department deputy spokesman Tom Casey said.

David Welch, the assistant secretary of state for the Middle East, has talked to Egyptian authorities about the situation, Casey said, but he didn't offer details. He said the Egyptians take border security seriously and that he has no indication the situation has affected Israeli-Palestinian relations for now.

Tens of thousands of Palestinians on foot and on donkey carts poured into Egypt from Gaza Wednesday after masked gunmen used land mines to blast down a seven-mile barrier dividing the border town of Rafah.

The border breach was a dramatic protest against the closure of the impoverished Palestinian territory, imposed last week by Israel. The Palestinians were stocking up on goods made scarce by the Israeli blockade. The border fence had divided the Rafah area into two halves, one on the Egyptian side and one in southern Gaza.

Earlier Wednesday, Secretary of State Condoleezza Rice offered a muted response, saying in Switzerland that the U.S. wants to see stability in the region, but that "most importantly both the security concerns of Israel and the humanitarian concerns of Gazans be met."