FRAMINGHAM, Mass. -- Massachusetts residents are being urged to go about their normal business Thursday as authorities search for four Chinese nationals -- individuals described by the FBI as potential terror suspects.

State and federal officials continue to investigate reports that four suspects may have headed to Boston posing a possible terror threat.

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Steve Sbraccia Reports On Investigation Video:Gail Huff Reports On Terror Threat HOMELAND SECURITY Boston FBI Office Massachusetts Emergency Management Agency Our Homeland Security Page Images Of Suspects Preparedness Tips Alert Levels Change Your Behavior? Five Levels Of Alert System CONTACT INFORMATION Report suspicious activity to the FBI. Web Site: FBI Tips, Leads Hot Line: (866) 483-5137 SUSPECT PICTURES Chinese Nationals Sought By FBI FBI: 617-742-5533

An anonymous tipster phoned information to California authorities that four Chinese nationals and two Iraqis were headed to Massachusetts, prompting Massachusetts Emergency Management Officials in Framingham to launch an investigation and go on limited activation status.

NewsCenter 5's Gail Huff reported that representatives from eight different state agencies are involved in the investigation, including state police, the Department of Health, National Guard and the governor's office, which is working closely with the FBI.

Gov. Mitt Romney returned to Massachusetts from Washington, D.C., late Wednesday, cutting short his trip to the nation's capital for Inauguration festivities. While there, he conferred with Homeland Security Chief Tom Ridge.

"In this case I think we have a threat which is uncorroborated, not necessarily reliable, an anonymous source, but the information was quite specific and because of that specificity we're taking this quite seriously," Romney said.

In Boston, hazmat crews and bomb-sniffing dogs were employed as officials increased security in search of the four Chinese nationals and two Iraqi nationals who may have illegally entered the U.S. via the Mexican border several days ago, possibly in possession of some kind of contraband device. They said reports the individuals may have had materials for a dirty bomb were unsubstantiated.

The threat notice was phoned to California Highway Patrol in San Diego Wednesday via cell phone. An anonymous caller said he smuggled the suspects across the border. He refused to give his name and did not show up for a meeting with investigators, but he did leave pictures and names of some of the suspects at a drop site.

Four of the suspects were identified as Zengrong Lin, Wen Quin Zheng, Xiujin Chen and Guozhi Lin. None of the individuals have appeared on any previous terrorist watch lists, authorities said.

"The intelligence information indicates that people were going to be traveling to New York City and then they were going to be coming to Boston and that the threat was targeted at Boston or the Boston-area. We don't have any reason to believe that they're in Massachusetts at this point, don't even know that they're coming here, but the information is sufficiently specific that we wanted to look into it very, very carefully," Romney said.

He said that uncorroborated terror threats are not uncommon.

"We don't know whether that's a reliable tip or whether it's something designed to make people fearful, to interfere with the inauguration festivities perhaps, or who knows the reason a tip may come in from an anonymous source, but anytime something of this nature comes up, you just can't afford to let them sit by the side of the desk, you have to take them seriously, investigate them, and once they've been thoroughly investigated and dismissed, then you can go on," Romney said.

The FBI said it receives these types of calls often and takes precautionary steps when it gets them.

"Basically, what you have here is information that we often get. It's uncorroborated at this time," said FBI Spokeswoman Gail Marcinkiewicz in a statement. "It's been passed on to our law enforcement partners and we're working it aggressively."

The terror threat level in Boston has not been raised.

New Hampshire Gov. John Lynch also returned from the inauguration festivities in Washington to offer assistance to Massachusetts in the event it was needed.

Anyone with information about the threat or the suspects is asked to call the FBI at 617-742-5533.