Walsh: Boston On High Alert Following ISIS Threat Alluding To New York City

BOSTON (CBS) -- After ISIS produced a video containing veiled threats against New York City, Boston is on heightened alert.

"In the wake of the Paris attacks, we should be on alert," says Mayor Marty Walsh.

He adds that there is no credible threat against Boston, but ever since 9-11, the city has trained its first responders for a terrorist attack, even chemical.

"We train frequently for chemical and biological attacks, and I feel we are prepared,"  Boston Police commissioner William Evans said.

"I feel confident and comfortable, but we're on alert," Walsh said.