PORT-AU-PRINCE, Haiti (AP) _ Men firing guns burst into a Roman Catholic church 58 miles north of the capital, forcing an outspoken anti-government priest and 20 other people to flee, one of the victims reported.

After the attack Sunday night, the cars in which the group escaped encountered a roadblock just outside the town and were attacked by armed men said to be supporters of former dictator Jean-Claude Duvalier, said Axel Martial, a layman who was there.

Radio Haiti Inter said three priests suffered superficial injuries from stones and shattered glass and were hiding Monday at a ''safe place'' in Port- au-Prince.

In the group was the Rev. Jean Bertrand Aristide, who leads the Haitian church's left wing. Aristide recently was transferred out of the capital to an isolated parish, but the transfer was rescinded after a sit-in and hunger strike by young people at the capital's Notre Dame cathedral.

According to Radio Haiti Inter, Aristide and several other priests and nuns were invited to the small church near St. Marc, 58 miles from Port-au-Prince, to say a Mass for more than 70 landless peasants massacred July 23 in Jean Rabel by sharecroppers working for landowners.

As the local priest was introducing Aristide, gunmen who residents said were Duvalier supporters burst into the church shooting, and beat several members of the congregation. Duvalier fled the country Feb. 7, 1986 and the Caribbean island nation has been governed since by a military-civilian junta led by Gen. Henri Namphy.

Aristide and three other priests - Jean-Marie Vincent, a leader of the peasants killed at Jean Rabel; Antoine Adrien, and William Smart - fled in a car toward Port-au-Prince, followed by others from the church.

Martial said in a telephone interview Monday that soldiers searched the priests' car at a police post just south of St. Marc.

Less than 100 yards farther on, he said, they encountered a roadblock with 50 men armed with guns and machetes. The radio identified them as ''notorious Macoutes'' - former members of the private Duvalier militia known as the Tontons Macoutes.

As the priests sped through the roadblock, the attackers shouted ''Communists 3/8'' at them, broke the car's windows and appeared to injure some of the priests with stones, Martial said.

Martial's car did not make it through the blockade. ''They beat me with rocks and sticks, thinking I was Aristide,'' he said. ''When they saw I was not, they let me go.''

Catholic missionaries trying to organize poor Haitians have come under attack recently from soldiers and former Tontons Macoutes.

Radio stations reported several instances last week of missionaries in Jeremie, on the southwest peninsula, being intimidated and beaten by soldiers and peasants working for landowners.

Attackers sacked a missionary store in Gros Morne, 110 miles north of the capital, early this month. The missionaries had fled.

A week after the killings at Jean Rabel, soldiers attacked the mission of the priests who helped organize the peasants, seeking to arrest them, and sharecroppers burned down the mission. The priests were able to escape.