NEW YORK -- Federal transportation officials began investigating on Wednesday what caused a NewsChannel 4 helicopter to spin out of control and crash on a Brooklyn rooftop, causing minor injuries to the reporter and two pilots on board.

CHOPPER 4 CRASH CAUGHT ON TAPE Images Of Crash Video Of Crash Analysis Witnesses (Above Pictures Courtesy WABC-TV) INVESTIGATION BEGINS Pilot Speaks Out Pilot Reacts To Crash Families Displaced NTSB Launches Investigation Crew Recovering Dan Rice's Perspective Chopper 4 Hoisted Slideshow (Above Pictures Courtesy WPIX-TV) VIRTUAL TOUR Inside Chopper 4: Behind The Controls VIEWER MESSAGES Read: Messages To The Crew III Read: Messages To The Crew II Read: Messages To The Crew I E-Mail: Leave A Message For The Crew

Reporter Andrew Torres and the pilots were in stable condition at Brooklyn hospitals, a day after they had flown to the area to cover a shooting for WNBC-TV. The careening chopper clipped a four-story apartment building and then crashed in pieces onto the neighboring two-story building.

The helicopter pilot had reported a "tail rotor failure" to air traffic controllers at Kennedy International Airport moments before the 6:21 p.m. crash, according to Jim Peters, a Federal Aviation Administration spokesman.

Luke Schiada, a senior investigator for the National Transportation Safety Board, said Wednesday that officials had not identified a cause, but were interested in the pilot's report.

"We're obviously going to take a closer look at that," he said.

The tail rotor, which essentially counteracts the force created by the turning of the main rotor, could fail in several different scenarios, aviation expert Walt Lamon said. He also said that a tail rotor failure is generally not a problem that would be identified during preflight inspection.

"Everyone in the industry will look at this for causes and ways that this can be avoided," he said. Helicopters "have a good safety record, it's a relatively safe activity, and there will be efforts focused on making it safer because of this."

Investigators also will be examining footage of the crash shot by another news station. The NTSB expects to issue a preliminary report in about five days, and a final ruling in several months.

"We have a lot more work still to do and we don't want to jump to any conclusions," Schiada told reporters during a briefing at the crash site, where two other news helicopters circled overhead.

Cranes removed the mangled pieces of the WNBC-TV helicopter, which was owned by Horsham Valley Airways, and placed them on flatbed trucks Wednesday morning. The California-based company refused to comment on the crash or give further information about the three passengers, who are their employees.

Jill Nicolini, who covers traffic and breaking news each day from a helicopter for WB11's "Morning News," said she was shocked, when she saw the wreckage, that the passengers survived.

"It does make you aware that it can be a dangerous job, but if you have a passion and love for flying like I do and you know how statistically safe flying is, I'm confident," said Nicolini, who is training for an airplane pilot's license.

There were 212 civilian helicopter crashes nationwide in 2003, 37 with fatalities, a slight increase from 2002, which saw 205 crashes, 26 that were fatal, according to the Helicopter Association International, which compiles FAA and NTSB data.

In 1978, before a push during the 1980s to improve helicopter safety, there were more than 300 crashes.

In 1986, Jane Dornacker, a traffic reporter for WNBC Radio in New York, was killed when her helicopter crashed into the Hudson River. The pilot was critically injured.

As the chopper plunged toward a pier, listeners heard Dornacker scream at the pilot, "Hit the water! Hit the water!"

The Federal Aviation Administration later accused the helicopter company of making faulty repairs. Dornacker's daughter reached a $325,000 settlement with the owner and manufacturer of the helicopter.

Earlier in 1986, Dornacker and another pilot escaped unharmed when a WNBC traffic helicopter crashed into the Hackensack River in New Jersey.

In December 1998, a WNBC-TV helicopter crashed in a shower of sparks into the Passaic River in New Jersey. The pilot and a reporter were pulled from the water by workers at a riverside plant and suffered only cuts and bruises.

WNBC debuted television news via Chopper 4, April 18, 1995, on "Live at Five." It provides NewsChannel 4 with live aerial shots for up-to-the-minute coverage of breaking news