Updated

U.S. investigators want to speak with a small number of people in Paris who failed to show up for boarding flights to Los Angeles that fell under close scrutiny in a possible terrorist plot, including one pilot-trainee, a U.S. official said Friday.

The official, speaking on condition of anonymity, said investigators hope to resolve concerns that some passengers aboard those flights might have intended to use them to launch terror attacks against the United States. One of them was receiving pilot training but was not yet certified, the official said.

Discussions between U.S. and French officials led to the cancellation of six Air France (search) flights between Paris and Los Angeles on Wednesday and Thursday.

On Friday, Air France Flight 68 from Paris to Los Angeles, scheduled for 1:30 p.m., was delayed for hand luggage checks, the air carrier said. The flight was roughly two-and-a-half hours late. Air France Flight 70 to Los Angeles was scheduled for 7 p.m. but left at 9:45 p.m., according to Charles de Gaulle airport, but there was no information available on what caused the delay.

An American Airlines flight at Indianapolis International Airport was evacuated Friday after a flight attendant found a suspicious-looking device onboard. Police determined the object posed no danger.

U.S. officials also were talking to counterparts in other countries.

"We're clearly in a time when the terrorist threat is very real, the efforts that Al Qaeda makes to plot and plan to attack us is constant and continuous," said Rep. Jim Turner (search), the senior Democrat on the House Select Committee on Homeland Security (search). "It is not anything that we can take lightly."

Turner said he was waiting for formal briefings from the department for more information about the cancellations, and said initial reports indicated the government had dodged another terrorist strike.

Rep. David Dreier, R-Calif., also a member of the Homeland Security panel, said it was too early to tell whether a potential attack was thwarted.

"Clearly, there was traffic, chatter as they call it, that indicated that a threat was there," Dreier said.

The flight cancellations added to Americans' unease during the holidays after the Bush administration increased the national threat level to its second-highest level, orange.

White House spokesman Scott McClellan said Friday the government was working to "make sure we are doing everything we can to protect the American people and prevent possible attacks from happening in the first place."

After the Air France cancellations, French investigators questioned seven men pointed out by U.S. intelligence but found no evidence they planned to use a Los Angeles-bound jet to launch terror attacks against the United States, French authorities said.

Officials in Washington and Nevada disputed a published report Friday that the flight cancellations thwarted a possible terrorist plot to crash an airliner in Las Vegas. Jerry Bussell, Nevada Gov. Kenny Guinn's adviser on homeland security, said federal Homeland Security officials told him there was no known threat to Las Vegas.

Meanwhile, U.S. counterterrorism officials were turning to possible threats next week that might target large, public gatherings, such as New Year's Eve celebrations. One U.S. official said there was no specific information such an attack was likely, but said such gatherings would obviously be an attractive target for terrorists hoping to inflict large-scale casualties.