Hartford — A threat of a violent attack at the Connecticut state Capitol on Tuesday came from a secured, possibly foreign-owned phone and was similar to threats phoned to at least four other states, police said Wednesday.

"It's pretty much untraceable," Lt. Gregory Wimble, spokesperson for the Connecticut State Capitol Police, said of the call, received by the Hartford Police Department around 3:20 p.m. Tuesday.

"We knew we had nobody on the property," Wimble said.

Capitol police video surveillance quickly confirmed there were no armed people on the 14-acre Capitol grounds, he explained.

The caller threatened violence and claimed to be on the grounds with a weapon and possibly explosives.

Because of the explosives threat, the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives was brought in to aid in the investigation.

Capitol police locked down public entrances while vehicles were searched and bomb-sniffing dogs were deployed on the Capitol campus, which includes the Legislative Office Building.

Debate continued in the House and Senate and staff, the public and lobbyists mingled as usual during the lockdown, which began around 3:30 p.m. Tuesday.

Legislative leaders of both parties praised Capitol police for how they handled the situation.

"I was informed in a perfectly timely manner on Tuesday by the Capitol Police Department on its response to a potential situation on the Capitol grounds while business was being conducted," House Republican Leader Vincent J. Candelora said in a statement. "The police have always maintained efficient and clear communications with those they are sworn to protect.

"This was a textbook response on their part, and at no time did I or anyone in my office feel threatened or exposed to potential harm," he continued. "I applaud the police efforts and commend them on their professionalism."

Senate President Pro Tempore Martin M. Looney, a New Haven Democrat, said in an emailed statement of his own, "Although unfortunate, yesterday's threat on the state Capitol served to underscore the preparedness and professionalism of the Connecticut State Capitol Police force and its partners."

"Additional police resources arrived at the Capitol complex within minutes of receiving a call for assistance," Looney continued. "Officers methodically secured and cleared the grounds of threats, all while legislative deliberations proceeded without interruption. I applaud Chief Luiz Casanova and his department for once again ensuring the safety of the Capitol community and its visitors."