Four more people were killed yesterday in Lebanon's northern port of Tripoli, and the city shut down in mourning for 16 others killed in several attacks by gunmen Thursday.

Five bombs exploded elsewhere in Lebanon, The Associated Press reported. One of the bombs was planted in a watermelon and directed against Israeli troops, but no casualties were reported.

The watermelon bomb blew up in the southern Lebanese market town of Nabatiyah, causing slight damage to a fruit stand, the Tel Aviv military command said. The other bombs destroyed a grocery in the Palestinian refugee camp of Sabra in West Beirut, and wrecked a bakery, a grocery and an electrical tools shop--all owned by Palestinians--in the Israeli-held southern port of Sidon.

Tripoli police said a Lebanese Army corporal was shot to death and that the bullet-riddled bodies of three laborers were discovered in the city.

In another development, Israeli troops lifted a week-long blockade of the southern Lebanese village of Deir Qanoun An-Nahr. Israeli soldiers sealed off the village after three Israeli soldiers were killed and two others wounded near the town on June 9. Leaders of the Shiite Moslem village of about 4,000 said the Israelis took 70 to 75 men for questioning.

In Damascus, Syria, Palestinian guerrillas said that they and Lebanese "resistance forces," fighting under a joint command, had carried out most of the recent attacks on Israeli soldiers in Lebanon. The guerrillas are opponents of Yasser Arafat, chairman of the Palestine Liberation Organization. Arafat said Sunday that a "higher Palestinian-Lebanese command" had been formed to coordinate operations against Israel in Lebanon.