JACKSONVILLE, Fla. -

SWAT teams were on high alert in Watertown, Cambridge and Boston all day Friday looking for suspect Dzhokhar Tsarnaev, a suspect in the Boston Marathon bombings.

SWAT officers are highly trained officers within a police department.

Former Jacksonville Sheriff's Office SWAT Cmdr. Rick Parker spoke about how a team handles this type of situation.

The exchange of gunfire caught on cellphone video Friday morning tells it all -- the bombings suspects were willing to fight to their death. Already blamed for killing a police officer and critically injuring another, police worked with an abundance of caution in their manhunt for Tsarnaev.

"We're not talking about a burglary suspect. We're talking about a Chechen terrorist," Parker said. "So the operational tempo is completely different today. The level of seriousness is completely different today for those guys in Boston."

Parker, who's now a law enforcement professor, says the manhunt in Massachusetts is probably the largest he's ever seen on American soil, with nearly 10,000 law enforcement officers believed to be involved. He says local, state and federal SWAT teams and bomb squads are working together.

Combining forces isn't unheard of. It happened in northeast Florida in 2010 when police searched for double-murder suspect Christopher Kilgore near the Duval-Clay county line. JSO and Clay County deputies teamed up, and officers were able to shoot and kill the heavily armed fugitive.

"A good example of a smaller type model, where it can work and it can work very effectively," Parker said. "But you've got to problem solve quickly."

Parker says officer safety is a big priority in the Boston manhunt, but they're very well-trained. The people he's more worried about are the neighbors in the community where the suspect may be hiding.

"The citizens are asked to be locked up in their own homes," Parker said. "What are they going to do if confronted by this lone suspect right now?"