The death toll in Monday's police assault on a radical group's stronghold climbed to 11 today, including four children, as Mayor W. Wilson Goode, under intense pressure, dug in his heels against criticism.

Fire investigators searching the charred rubble of the headquarters of MOVE, a revolutionary, back-to-nature group, found five more incinerated bodies today. Officials said they expected to find additional remains of group members killed in the assault, in which police dropped a two-pound explosive device on the group's house; an ensuing fire destroyed it and 52 other row houses in a two-block area of west Philadelphia. Damage was estimated at $5 million.

Investigators said today they had also found two shotguns, a rifle, a machine-gun tripod, a second steel bunker and the remnants of several unidentified explosive devices in the ruins of the group's headquarters.

Goode, testy and nervous at a midafternoon news conference, defended the decision to drop the explosive device on the house, located in a densely populated, middle-class black neighborhood.

The mayor brushed aside a call to fire Leo Brooks, the city's managing director and Goode's eyes and ears at the scene. The call came from Hardy Williams, who represents the neighborhood in the state Senate.

Told that New York Mayor Edward I. Koch had said he would fire a police commissioner who recommended that a "firebomb" be used in an urban area, Goode said: "I think Mayor Koch should run his city and leave mine alone."

Goode, who delegated key decisions in the confrontation with MOVE to Brooks and Police Commissioner Gregore Sambor, said: "There will not be any scapegoats in this arrangement. I am fully and totally responsible. Everything that was done was done with my knowledge . . . . I am not second-guessing anyone in the field."

The mayor said he will appoint a commission within a week to review what occurred here.

And he stood firmly behind the actions taken by police and fire department officials. "What happened was an accident," he said. "There was no plan to destroy the house with fire or explosives."

Goode said officials had a "well-thought-out plan" to remove MOVE members from their heavily fortified compound and that "throughout the day Monday the plan worked. The only thing that went wrong . . . was the fire."

Sambor said today that MOVE members had spread "flammatory material" inside their row house and that the fire began there, and not on the roof. Asked why they would set fire to their headquarters, Sambor replied: "They have stated they were prepared to die. They initiated the action. They chose the site. They chose the manner in which everything would go down."

The scene at the corner of Osage Avenue and 62nd Street today was a grisly, stomach-wrenching one. All that remained of the row houses on either side of Osage were steel girders and charred brick walls.

Keith Goodwyn, 27, who watched Monday's events from his house a half block away, shook his head as he watched investigators sift through the wreckage of MOVE headquarters today.

"They dropped the bomb," he said of the police. "The bomb killed those people and destroyed the whole block. You just don't drop a bomb on children in the middle of the city."

As he watched, a large crane scooped rubble from the ashes of the MOVE house, dumping it in the street. Firemen in blue coveralls raked the debris, searching for remains.

Now and then, two men from the medical examiner's office stepped forward and placed some remains in red or green plastic bags and took them to a black van.

Many of those who watched said they did not blame Goode, the city's first black mayor, for what happened. And polling by two local television stations found that nearly two-thirds of the respondents approved of Goode's handling of the situation.

But in west Philadelphia and elsewhere, many people were still asking these questions:

Why was a neighborhood destroyed to save it from a small group of revolutionaries? Why were firefighters so slow to put out the blaze, which raged out of control for six hours? How did the people die? What started the fire? And, above all, why was an explosive device dropped on a rooftop?

"The situation was very poorly handled," said state Sen. Vincent J. Fuma, who visited the neighborhood today. "Although the mayor has an obligation and a right to rely on so-called professionals, at some point in time his own common sense has to tell him that when those professionals say they want to drop a bomb on a row house in Philadelphia, he has got to say no."

Goode attempted to answer some of the unresolved questions in his hour-long news conference.

The mayor said he would not have approved dropping the device had he foreseen the result. "I would have said no because the intent was to save lives, not destroy them," he said.

He said city managing director Brooks informed him of the plan to drop the device about 20 minutes beforehand. A police helicopter then hovered over the MOVE house and dropped a satchel that Sambor said contained two one-pound tubes of Tovex, a blasting material made by DuPont and described as similar to dynamite.

The object, Goode said, was to destroy a crude bunker, fortified with steel plates, atop the row house so that police could drop tear gas through the roof. The mayor said police had considered removing the bunker with a crane or ramming an armored personnel carrier into the house, but had rejected both ideas.

Police earlier had tried to knock the bunker off the roof with tons of water, and had shot canisters of tear gas into the building, which was reinforced with steel plates and tree trunks.

Police had also attempted to burrow into the basement of the house from an adjoining row house, but were met with more fortifications and armed MOVE members, Goode said.

Staff writer Milton Coleman contributed to this report.