Four sought in possible Boston terror threat
Mayor dismisses 'much misinformation circulating'
(CNN) -- State, federal and local authorities Wednesday were seeking four Chinese nationals wanted for questioning in connection with a possible terrorist threat to the Boston, Massachusetts, area, but they said the source of the information was "unknown and uncorroborated."
The FBI and the U.S. attorney's office identified the subjects of the search as Zengrong Lin, Guozhi Lin, Wen Quin Zheng and Xiujin Chen. None have appeared on government "watch lists," according to a joint statement.
"There is no further specific information regarding the city of Boston, nor is there any degree of specificity on the type of potential threat," the statement said. "As is done whenever we receive this type of information, all appropriate investigative steps are taken."
The information is being investigated by the Boston Joint Terrorism Task Force, according to the statement.
In Washington, Massachusetts Gov. Mitt Romney told reporters an anonymous phone tipster reported that all four had been smuggled into the United States from Mexico.
"The source is anonymous," he said. "But it is specific in that it mentions a location where individuals were dropped off -- the location is New York -- and it identifies a location where a threat might be directed in -- the location is Boston."
He described the information that triggered the alert as "uncorroborated," and its reliability as "uncertain."
Earlier, multiple law enforcement sources told CNN the caller reported that four Chinese -- along with two Iraqis -- were smuggled over the U.S. border from Mexico and were headed to Boston.
They were either carrying or planning to receive some unspecified dangerous materials, the sources said.
Jan Caldwell, an FBI spokeswoman in San Diego, California, said agents get hundreds of tips each day like the one that resulted in Wednesday's alert.
"We have some excellent leads in this investigation," Caldwell said. "I have no doubt that we will find a resolution to this sooner rather than later."
Romney said there was nothing to indicate the group was in Massachusetts as of Wednesday night, but that the state emergency management agency and other law enforcement agencies were at a heightened state of alert.
He said he was cutting off his trip to President Bush's inauguration to return to Boston -- in part to reassure state residents about the situation.
"I'm going to be sleeping in my bed in Massachusetts tonight, and I feel perfectly safe doing so," he said.
Boston Mayor Thomas Menino specifically dismissed reports of a plot involving a radiological "dirty bomb" or fuel tankers. He called on the public to remain calm amid "much misinformation circulating."
"I encourage you all to go about your business, as I will be doing this evening," Menino told reporters.
CNN's Jeanne Meserve contributed to this report.