Less than 12 hours after catastrophic acts of terrorism leveled New York’s World Trade Center towers and ripped through the Pentagon, the streets in the nation’s capital were eerily quiet.

Even as firefighters extinguished the last flames at the Pentagon and World Trade Center and began a rescue effort for hundreds of people feared dead, the destruction and chaos from earlier in the day seemed as confusing and horrific as when it all began.

Just before 9 a.m. Tuesday, an American Airlines Boeing 767 en route from Boston to Los Angeles sharply changed direction and locked on a collision course with the World Trade Center. It slammed into the side of one of the twin 110-story towers with amazing force.

Twenty minutes later, a United Airlines Boeing 767 on the same route hit the other twin tower in a spectacular explosion of fire and debris.

Moments after, television cameras captured the desperate pleas of people on the upper floors of the building gasping out of windows for oxygen and help. What some originally thought was debris falling from the upper floors turned out to be office workers jumping to escape.

Within an hour, reports from D.C. told of an explosion in one section of the Pentagon. By late afternoon, officials confirmed an American Airlines 757 that took off from Washington Dulles Airport en route to Los Angeles crashed into the building.

At about 10 a.m., officials in Pittsburgh said a United Airlines 757 en route from Newark, N.J. to San Francisco crashed in a rural area 80 miles southeast of the city.

To add to the devastation, early reports in the District said a car bomb detonated outside the State Department and another explosion had occurred at the Capitol. Federal officials later said those reports were false.

Rescue efforts continued through the night and may last for a number of days. Rescuers Tuesday evening reached some areas of the Pentagon and World Trade Center, where fires and smoke began to subside.

In a nationally televised address Tuesday night, President George W. Bush gave the first clear estimates of casualties. He said thousands of people may have died in the explosions.

Hospitals in Washington estimated hundreds of people arrived with injuries, but put the death toll under 100. That number is expected to rise steadily as bodies are recovered from the wrangled concrete of the Pentagon. The same outcome is expected in New York as the search effort continues to find victims in the rubble.

President Bush called the strikes a “despicable act of terror” and said the “military is powerful and it is prepared” to respond.