An SSNP member was also hit in the head by a bullet near the mountain village of Sofar.
At least 15 people were hurt in scuffles elsewhere, mainly in Christian areas.
Lebanese soldiers fired into the air to keep stone-throwing crowds apart in Beirut and on a highway to the north.
Dozens of protesters blocked off the only road leading to Beirut's international airport at the start of the stoppage - which began at 04:00 GMT.
"Even with the entire world on his side, Siniora will lose if he hasn't got the Lebanese on his side".
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Several Arab and international airlines suspended flights to Beirut, and shops and businesses in the capital remained closed.
Black smoke billowed over Beirut as the army deployed armoured vehicles at major crossroads along with hundreds of soldiers.
Lebanese security forces struggled to open blocked roads obstructed by protesters.
"Siniora out, down with the government," Hezbollah followers chanted as they lit tyres in central Beirut, close to the prime minister's office.
Hassan Fadlallah, a Hezbollah MP, told Al Jazeera that the government was to blame for the protests.
"These people had to do this to make their voice reach the government. What would the people do when the government becomes a dictatorial one?," he said.
So far the Lebanese army has had minimal conflict with protestors intervening only to disperse groups fighting amongst each other.
As a consequence, says Al Jazeera's correspondent in Beirut, Rula Amin, the only option the goverment has is to call its own protestors onto the streets.
Amin says both sides know the risk of such an action and that widespread violence could erupt but both are very stubbornly entrenched in their positions and are not prepared to compromise.
The opposition, led by the Shia group Hezbollah, is calling for veto power in the cabinet and new elections to be held.
The Western-backed government of Fouad Siniora, the prime minister, has shrugged off the demands.
Instead, it is preparing for an international aid conference in Paris on Thursday that it hopes will yield billions of dollars for Lebanon's economy, but has been criticised by the oppostion for increasing the country's debt problems.
Ahmad Fatfat, the Lebanese minister of Youth and Sports told Al Jazeera that the strike was an "aggression against the Lebanese people".
Samir Geagea, head of the Christian Lebanese Forces, and an opponent of the strike, said the protests had nothing to do with democracy or freedom.
"This has been transformed into a coup d'etat. It is a revolt in every sense of the word," he said.