Clashes at a Beirut university between students from rival political factions have left at least two people dead and more than 20 injured, reports say.
The Lebanese army has imposed a dusk-to-dawn curfew in the capital, Beirut, after clashes between students from rival political factions.
Fighting between government supporters and opponents broke out at the Beirut Arab University in the south of the capital and moved on to the streets.
Two people were reported to have been killed and at least 20 others injured.
The army has declared an overnight curfew in Beirut from 2030 (1830 GMT).
It comes two days after three people died in clashes amid a general strike called by the militant Hezbollah group.
It follows a crippling Hezbollah-led opposition strike on Tuesday, during which three people died in clashes.
In Paris, foreign donors pledged $7.6bn (£3.5bn) to help Lebanon recover from last year's conflict between Hezbollah and Israel and a huge public debt.
Hezbollah, which is backed by Syria and Iran, has led mass demonstrations and strike action since the beginning of December to try to force Prime Minister Fouad Siniora's pro-Western government to resign.
The biggest pledges came from Saudi Arabia, the US, France and the EU.
Hezbollah's supporters see the government as being too close to the West, and accuse it of bankrupting Lebanon.
Lebanese Prime Minister Fouad Siniora, who attended the conference, said he was "really pleased with the level of financial support".
However, the BBC's Caroline Wyatt in Paris says the Lebanese government had to promise to implement potentially unpopular economic reforms, which could create further difficulties with the Hezbollah-led opposition.
Campus brawl
Campus brawl
The latest trouble started as a campus row between Sunni supporters of the government and Shia opponents but it flared rapidly from a student fist fight to violent clashes between local supporters of the two sides.
The latest violence started as a row between Sunni supporters of the government and Shia opponents at Beirut's Arab University but it flared rapidly from a student fist fight to violent clashes between local supporters of the two sides.
Troops were called in to try to separate the two sidesClub-wielding students hurled rocks and other missiles at each other as fighting spread across the capital.
Troops were called in to try to separate the two sidesClub-wielding students hurled rocks and other missiles at each other as fighting spread across the capital.
Television pictures showed youths moving through the streets, brandishing makeshift weapons and vandalising cars.
Television pictures showed youths moving through the streets, brandishing makeshift weapons and vandalising cars.
As the row escalated supporters of the Shia Hezbollah movement called in help, and residents from the local Sunni neighbourhood also joined in.
As the row escalated supporters of the Shia Hezbollah movement called in help, and residents from the local Sunni neighbourhood also joined in.
Armoured vehicles full of soldiers moved in, firing shots in to the air, trying to keep the two groups apart.
Armoured vehicles full of soldiers moved in, firing shots in to the air, trying to keep the two groups apart.
The BBC's Jim Muir in Beirut says the clashes erupted in a volatile area where the mainly Sunni population overlaps with Shia neighbourhoods.
The clashes erupted in a volatile area where the mainly Sunni population overlaps with Shia neighbourhoods.
He says gunfire continued to echo in the area after nightfall but police later said that order had been restored.
Gunfire continued to echo in the area after nightfall but police later said order had been restored.
The clashes reinforced fears raised by the general strike on Tuesday that a major flare-up of civil strife could break out if urgent action is not taken to defuse the explosive political situation, our correspondent adds.
The clashes reinforced fears raised by the general strike on Tuesday that a major flare-up of civil strife could break out if urgent action is not taken to defuse the explosive political situation, reports the BBC's Jim Muir in Beirut.
The violence came as foreign donors meeting in Paris pledged more than $7.6bn (£3.5bn) to help the country rebuild following last summer's conflict between Hezbollah and Israel.
Hezbollah, which is backed by Syria and Iran, has led mass demonstrations and strike action since the beginning of December to try to force Mr Siniora's pro-Western government to resign.
Have you been affected by the clashes in Lebanon? If you have any information you would like to share with the BBC you can do so using the form below:
Have you been affected by the clashes in Lebanon? If you have any information you would like to share with the BBC you can do so using the form below:
