TEGUCIGALPA, Honduras — Already volatile Honduras slid toward greater instability after soldiers blocked an airport runway to keep ousted President Manuel Zelaya from returning, and protests that had remained largely peaceful yielded their first death.

Police and soldiers blanketed the streets of the capital overnight Monday — enforcing a sunset-to-sunrise curfew with batons and metal poles.

The extended curfew added to the tension after a turbulent Sunday that saw soldiers clash with thousands of Zelaya backers who massed at the airport in hopes of welcoming home their deposed leader.

Zelaya's plane, on loan from Venezuelan President Hugo Chavez, arrived to find the runway blocked by military vehicles and soldiers under the command of the government that has ruled this Central American country since Zelaya's ouster last weekend.

His Venezuelan pilots circled around the airport and decided not to risk a crash.

Zelaya instead headed for El Salvador, and vowed to try again Monday or Tuesday in his high-stakes effort to return to power in a country where all branches of government have lined up against him.

"I call on the Armed Forces of Honduras to lower their rifles," he said late Sunday at a news conference, flanked by the presidents of El Salvador, Argentina, Paraguay and Ecuador, and the secretary-general of the Organization of American States, Jose Miguel Insulza, who flew there from Washington.

"I am risking myself personally to resolve the problems without violence," said Zelaya, who planned to fly later to Nicaragua. He urged the United Nations, the OAS, the United States and European countries to "do something with this repressive regime."

Insulza said he "is open to continuing all appropriate diplomatic overtures to obtain our objective."

But interim Honduran President Roberto Micheletti said he won't negotiate until "things return to normal."

"We will be here until the country calms down," Micheletti said. "We are the authentic representatives of the people."

Clashes broke out Sunday afternoon between police and soldiers and the huge crowd of Zelaya supporters surrounding Tegucigalpa's international airport. At least one man was killed — shot in the head from inside the airport as people tried to break through a security fence, according to an Associated Press photographer at the scene. At least 30 people were treated for injuries, the Red Cross said, after security forces fired warning shots and tear gas.

When Zelaya's plane was turned away, his supporters began chanting "We want blue helmets!" — a reference to U.N. peacekeepers.

Karin Antunez, 27, was in tears.