BEIRUT, Lebanon (AP) _ Palestinian guerrillas stormed out of their camps around Sidon before dawn today and dislodged Shiite Moslem militiamen from the surrounding hills, police said. At least 30 people died in the fighting.

Police also said 60 people were wounded in the battle for the Maghdousheh hills. Ambulances could not pick up bodies sprawled on roadsides because of the fierce fighting, which still raged at midday.

In Damascus, Syria, Druse leader Walid Jumblatt, a former ally of PLO chief Yasser Arafat, told The Associated Press his 5,000 militiamen would fight alongside Shiite Moslems to block the resurgence of the Palestine Liberation Organization in Lebanon.

Police said the Palestinian offensive was mounted behind a sustained rocket barrage from multibarreled launchers that destroyed positions in Maghdousheh's bluffs held by Justice Minister Nabih Berri's Shiite Amal militia.

''Hundreds of grenade-throwing guerrillas then burst out of the camps and took the hills surrounding the town of Maghdousheh and the nearby villages of Ghazieh and Tambourit,'' according to a police official in the port city of Sidon. He spoke on condition of anonymity.

Sidon-based reporters said the Palestinians controlled all the hills surrounding Maghdousheh, Ghazieh and Tambourit, a triangle of Amal strongholds stretching three to five miles southeast of Sidon.

Amal gunners have pounded the camps of Ein el-Hilweh and Mieh Mieh from the Maghdousheh hills since PLO guerrillas drove militiamen from the highlands east of the refugee camps last month.

A communique from the PLO's main Fatah faction said the operation was launched to stop Amal's bombardment of the Sidon camps ''once and for all.''

''Orders were issued to overrun Amal's fortified positions. Our forces have established full control over Maghdousheh and the surrounding hills. We have captured many pieces of armor,'' the communique said.

PLO guerrillas paraded at least three new armored personnel carriers and 10 jeeps with Amal's emblems.

An Amal communique accused the Palestinians of ''trying to occupy Lebanon to set up not only a Palestinian canton, but also to create an alternative homeland to Palestine.''

It pledged to ''liberate the land from the new usurpers.''

The guerrilla attack was another sign of the re-emergence of Arafat's forces in south Lebanon four years after the PLO was driven out by the Israeli invasion.

Amal, which is backed by Syria, has been fighting since May 1985 to prevent Arafat from regaining the Lebanon power base he lost in the Israeli invasion. Syria also opposes Arafat's return.

More than 1,000 people have been killed and 3,000 wounded in fighting for control of the camps since last year.

Today's casualties raised to 56 dead and 123 injured the overall toll of the PLO-Amal hostilities in the Sidon region since Friday.