N E W Y O R K, Sept. 14, 2001 -- Workers at the Pentagon have recovered the "black box" flight data recorders from the collapsed portion of the building, where a jet slammed into it during Tuesday's horrific terrorist attacks.
But in New York, where two planes leveled the World Trade Center on Tuesday, the rescue effort was hampered by rain.
The flight data recorders from the scene of the fourth hijacked plane, which went down in Pennsylvania at about the same time, were recovered on Thursday.
The rain in New York will help clear area of the dust that had been burning people's eyes and throats, but officials are concerned about the weight it will add to the wreckage.
Another concern is the structural integrity of the buildings in the area. Officials say they still need to make an assessment.
"[Officials] have to take each building, each area of each building piece by piece to evaluate where the load path is coming from," said Ted Beck, a structural engineer at the lower Manhattan site of where the twin towers stood. "And of course, make recommendations as far as what shoring has to be done temporarily [to] support what's up there."
Stormy Day Dampens Spirits
The rain in New York City follows a disappointing 24 hours: No survivors were found, and reports of firefighters that were recovered alive in a buried sport utility vehicle, which temporarily lifted spirits, were untrue.
Two firefighters had been temporarily trapped in an underground air pocket, and freed by other rescue workers, according to the Associated Press.(Because of the high amount of erroneous reports, the New York Fire Department has told all of their firefighters in the field not to comment to the press.)
Volunteer workers were also evacuated from a damaged office tower across the street from the World Trade Center, the news agency reported.
To assist with rescue and recovery efforts, President George W. Bush said he will activate up to 50,000 members of the National Guard and Reserve, according to the Associated Press. And the U.S. Senate approved a $40 billion emergency package that would support counter-terrorism, rescue and recovery efforts, according to Reuters.
Heavy Hearts, But the Search Must Go On
New York Mayor Rudolph Giuliani said 4,763 people were on the missing persons list, compiled from flight manifests and missing person reports from family, friends and employers of people who went to work at the World Trade Center on Tuesday. More than 2,000 survivors have been hospitalized.
Among the missing are about 300 firefighters, 30 city police officers and another 30 Port Authority police officers.
"The terrible reality of this is we may never be able to recover everyone, but we are going to try," the mayor said.
At the Pentagon on Thursday, officials said that no more survivors would be found there and some rescuers shifted their role to pulling bodies from the wreckage. About 190 people apparently died in the attack on the Pentagon, defense officials said.
Although officials have dashed hopes of finding more survivors in the Pentagon wreckage, search crews on Thursday said they planned to continue their diligent search of the collapsed portion of the nation's military headquarters, despite dangers that lurk in the ruins.
Perils for Rescue Teams
Some medical workers were discouraged at the dwindling number of patients they were seeing on Thursday. In some trauma centers, doctors were being told their services were no longer needed on Thursday. Today, reports are quoting medical personnel saying that they are not very busy right now at St. Vincent's.
Along with the perils of sifting through the smoldering, jagged ruins, medical experts say there are other possible health risks for the search teams.
Fire-retardant asbestos was used in the construction of the World Trade Center, which was completed in the early 1970s, and inhalation of it, along with the dust and smoke enveloping the search area, can be irritating for the rescue workers.
Search teams should wear masks over their noses and mouths, irrigate their eyes often, and seek medical treatment for an irritated throat, ABCNEWS' medical expert Dr. Timothy Johnson said.
For the rest of New York, Giuliani said on Thursday that tests showed the air is safe to breathe.
ABCNEWS' Geraldine Sealey, Alison Stewart, and ABCNEWS Radio contributed to this report.