"The team did well," Daughtery said yesterday afternoon as fire crews continued to search 65 Main St. for the cause of the explosion. "There are always things we can improve on. It's never perfect, but I'd give it a 91/2 out of 10."

The Fire Department received a call at 1:40 a.m. yesterday from a woman outside 65 Main St. who said she smelled gas. As the dispatcher ended the call, the four-family home exploded, destroying the house and shattering windows in houses and storefronts on Main Street. The woman, who made the call on a cell phone from inside a car, was uninjured.

Hopkinton police and firefighters immediately responded, cordoned off the area and began rescue efforts.

Ten of the 12 people inside the building made it out with injuries that were not life-threatening. The 4- and 5-year-old Carey sisters were trapped inside.

Lt. Francis Clark, a 28-year veteran of the Hopkinton Fire Department, arrived with the second truck.

"We're trained for response, response, response, but you have to think about all the aspects," Clark said.

Although his instinct, and that of his fellow firefighters, was to quickly rush in and save the two missing girls, the rescue crews must balance the risks and hazards of a dangerous situation, he said.

"We made the first victim rescue, and then the incident commander reported there was still an active gas leak," Clark said. "We withdrew to watch for possible secondary explosions while NStar shut down the gas."

Temporarily removed from their rescue mission, the firefighters felt helpless as they stood by scanning the debris as the sun began to rise.

"The situation was tough because of all the problems we were having," said firefighter Mike Duca, a 23-year veteran of the Ashland department who arrived with the first ambulance.

"It was heart-wrenching that we couldn't get in there and get the second girl out. I know all the firefighters are pretty devastated."

Duca and firefighter Bob Gemma took 20-year-old Poliana Compos, a pregnant woman who lived in the house, to Framingham Union Hospital. Compos walked out of her third-story window, which after the blast rested at ground level.

A hospital spokesman yesterday afternoon said Compos was resting and doing well.

Iris and Violet Carey weren't so lucky. By the end of the rescue, the death count was two.

"It's the nature of what we deal with," Clark said. "It's not an easy thing to do, but we have a job we have to finish. None of us can do this alone. It takes the help of all the firefighters and surrounding towns to assist."

Members of the Massachusetts Southern Fire District Technical Rescue Team responded, which meant Hopkinton was aided by Westborough, Southborough, Ashland and Milford firefighters. Marlborough firefighters also assisted.

"The call went pretty well," said Lt. Steve Slaman, a 13-year veteran of the Hopkinton department. "But the thing that's in the back of your mind is the devastation for the parents of the two kids.

"We try not to think about that too much until we have the call completed. If you could change that element of the call, you could say a lot of things went even better - but you can't."

Hopkinton police and fire attended a critical incident stress debriefing session yesterday. Daugherty said he will continue to meet with the department to discuss the incident, what went right or wrong and how to improve.

"The guys are still dealing with the situation," he said. "We'll see what happens as the next couple of days go by."