MASSAWA, Ethiopia (AP) _ The Soviet-built MIG jet fighter screamed over this Red Sea port at 6 p.m., racing down the coast from the north. Then came what sounded like a single explosion, followed by a violent shaking.

About 60 Eritreans - mostly women and children - sat in the basement of one home. It is their daily shelter from sunup to sundown from the threat of Ethiopian air raids on the strategic city of Massawa.

The rebel Eritrean People's Liberation Front captured the city Feb. 11, three days after launching a major new offensive in its 29-year war for independence.

A series of seemingly random attacks on Massawa by the Ethiopian air force began April 4. Two were staged April 22, bringing the total to six last month.

In the late morning, a MIG fired a single rocket toward the city's port facilities. It struck bare ground, toppling a nearby shed already damaged in a previous raid and causing one slight injury.

The evening raid, however, was devastating.

It dropped not one but two cluster bombs on a poor residential and market area about 800 yards away across a narrow causeway. A pillar of smoke rose several hundred feet over the target.

Many of the children cried in fear as they hid in the basement. Some of the women were moaning softly or crooning comfort to the young as the plane flew overhead.

Except for some nearby warehouses that stored donated grain meant for famine victims in Eritrea, Massawa's port itself has been undamaged. About 25 tons of wheat and other foodstuffs were destroyed in earlier raids.

''These raids are against civilians. They are designed to kill and terrorize the people,'' said Haile Menkerios, an economist who sits on the rebel central committee.

The Ethiopian government has denied it purposely targets civilians, but there were no rebel military installations anywhere near the scene of the latest air attack.

Visiting journalists arrived at the scene of the latest strike just as rescue efforts were beginning. The bodies of dead and wounded were strewn about. Many victims were children.

The raid, just before sundown, came as residents were beginning to emerge from hiding. Previous raids have taught them to stay sheltered during the day from an air force that usually flies on a 9-to-5 schedule.

''They've never come so late,'' said Menkerios of the evening attack. ''This was deliberate. They knew they'd find people out and about at this hour.''

The rebels later said 50 people died and 110 were injured the night of April 22. That nearly doubled the death toll from the previous five raids, bringing the combined fatality count to 110. More than 350 people have been injured, many of them seriously.

Some of the dead were loaded on trucks. Others were buried in a nearby mass grave hastily dug by a bulldozer. The city has been without electricity and running water since its capture by the rebels in February, and storage of bodies in the heat is impossible.

The Eritrean rebels accuse Israel of supplying the cluster bombs to the Marxist government of President Mengistu Haile Mariam. Both the Ethiopians and the Israelis deny it.

A cluster bomb explodes before hitting the ground, showering an area with dozens of smaller bombs, each carrying roughly the explosive force of a mortar round. They are particularly effective against massed troop formations.

Massawa is one of two strategic harbors that have traditionally handled most of Ethiopia's trade and international relief supplies for millions of people threatened with starvation in the face of war and drought.

The Eritrean Front has been fighting for control of Ethiopia's northernmost province since 1961, a year after the former Italian colony of Eritrea lost its autonomy and was forcibly annexed by the late Emperor Haile Selassie.

Rebels hold other towns and villages in Eritrea and, with backing from other guerrilla armies, are seeking to overthrow the Marxist regime.