Gaza City, Gazy Strip ? Israel ordered the Gaza-Egypt border crossing closed just hours after it was partially opened for the first time in weeks, European Union and Palestinian officials said Thursday.

The crossing was to have been opened for two days to allow hundreds of people stuck in Gaza to leave after a weeks-long closure imposed during Israel’s military offensive in the coastal strip.

Israel informed European monitors the crossing had to shut because there was a high security alert, officials said.

“We received a warning from the (Israeli army) that for security reasons the terminal will be closed. They were saying there were suicide bombers or something like that,” said Maria Telleria, a spokeswoman for the European border monitoring mission.

Military officials said Israel decided to close the border crossing due to specific threats.

The crossing had been opened to allow students, business people and some people requiring medical treatment to travel to Egypt, Telleria said.

About 500 sick people, many of them cancer patients, were given permission to cross the border for treatment, said Dr. Omar Shehada, a Palestinian Authority official responsible for overseas medical treatment.

People would not be allowed to cross from Egypt into Gaza.

A senior official on the Palestinian side of the border said no more than 80 people needing medical treatment managed to cross into Egypt. More than 4,000 people were waiting to cross when the border was closed, said the official, who spoke on condition of anonymity because he was not authorized to speak to the media.

The border was closed after Hamas-allied militants captured an Israeli soldier, Gilad Shalit, during a cross-border raid on June 25.

The seizure triggered an Israeli offensive in Gaza aimed at freeing him and stopping rocket attacks on Israeli border towns.