The phone lines have lit up at the Boston Field Office of the FBI following yesterday’s bombshell disclosure by federal authorities that they finally know who stole $500 million worth of masterpieces from the Isabella Stewart Gardner Museum 23 years ago.

Chief Division Counsel Damon Katz confirmed this afternoon, “We have gotten tips and we are analyzing them and will act on them as appropriate.”

Katz added the FBI will not be releasing specific numbers.

“The numbers are in line with what we would expect,” he said. “We didn’t have a target number of tips. Our target is just to get that art back on the walls of the museum.”

Anthony Amore, the museum’s director of security, told the Herald today it was a tip from a citizen in 2010 who called in with “new information about some matters that we had been looking into” that ultimately led to yesterday’s blockbuster developments.

“That was followed by thousands and thousands of manpower by the FBI and myself,” Amore said.

With the museum’s $5 million reward — the largest private reward ever offered — still up for grabs for the paintings’ safe return, Amore said he, too, has been hearing all day from people both within and outside of Massachusetts.

“I think it’s a very interesting case to people,” he said. “I think people want to help.”

Thirteen works of art by masters from Rembrandt to Degas were stolen on March 18, 1990, by two men posing as Boston police officers who persuaded two night guardsmen they were responding to a call for help at the gallery.

Officials said yesterday that the investigation took on new energy in 2010, but didn’t specify why. They also refused to clarify what crime organization they believe the thieves were part of.

Richard DesLauriers, special agent in charge of the FBI’s Boston office, said in a press conference yesterday that investigators believe the paintings have “changed hands several times” over the years, and those who have them now may not be the original thieves.

He added that the missing art was taken to Connecticut and then Philadelphia, where the thieves tried to sell some of the paintings roughly a decade ago. The FBI knows the identities of the suspects, but officials have refused to release their names, citing the ongoing investigation.

Matt Stout contributed to this report.