MONROVIA, LIBERIA, SEPT. 11 -- Troops loyal to slain President Samuel K. Doe bombarded rebels from atop the executive mansion today, and a West African leader said Doe's death will make it more difficult to end Liberia's civil war.

Two days after rebels led by Prince Johnson attacked Doe and his entourage at the headquarters of a West African peace-keeping force, wounding the president and taking him captive, survivors from Doe's elite presidential guard aimed heavy artillery set up on the roof of the seaside executive mansion at the rebels and the war-ravaged city.

Gambia's president, Dawda Jawara, said Doe's men had asked the five-nation West African peace-keeping force to help them leave the capital. Jawara said aid would be offered on humanitarian grounds.

"I think it is now urgent to try to do something about protecting these 230 or so Doe supporters from factional or tribal revenge," said Jawara, chairman of the 16-member Economic Community of West African States (ECOWAS).

ECOWAS ordered the 4,000-member task force into Liberia last month to help quell the 8 1/2-month-old civil war, often marked by tribal fighting. Jawara, who was visiting Zimbabwe, said that rather than speeding the war's end, Doe's death Monday likely would increase bloodshed.

After capturing Doe Sunday, Johnson had said he would be court-martialed, but on Monday the Liberian president was reported dead.

The West African force's commander, Lt. Gen. Arnold Quainoo of Ghana, said today that 78 people were killed when Johnson's men attacked Doe's entourage on Sunday.

Quainoo said in a statement that Doe told him he had come to express his surprise that Quainoo had not paid him a courtesy call.

The statement said: "General Doe talked at length to the effect that he was not ready to submit the sovereignty of his country to any power or indeed regional organization."

The statement said Johnson and about 40 of his men then arrived and protested Doe's visit. An argument ensued that degenerated into a shootout. Quainoo and other West African officers tried to persuade Johnson and his men to stop, "but failed, except that they did not kill Doe, who was shot in the legs and taken away," the statement said.

Reuter reported the following from Freetown, Sierra Leone:

Mohamed Ibn Chambas, deputy foreign minister of Ghana, said Doe's capture created "an embarrassing situation which has exposed the difficult and complex posture" of the West African peace-keeping force.

Western diplomats in the Ivory Coast capital of Abidjan said the Sunday incident had proven the difficulty and even the futility of the peace-keeping force's role.

"Doe ventured out of the executive mansion . . . with his bodyguards and was promptly slaughtered," one Western diplomat said.

"Now the fight is between {rival rebel factions}, and one wonders if {the West African force} is going to sit back and twiddle its thumbs."