BEIRUT --Lebanon released four generals held for nearly four years in the 2005 truck-bomb assassination of former Prime Minister Rafik Hariri after a U.N.-backed tribunal ordered them freed on Wednesday, setting off celebrations with fireworks and dancing.

One of the officers was cheered by a crowd of hundreds outside his house and another was hoisted onto the shoulders of family and friends and showered by rose petals as supporters danced and blew whistles.

Their release from a Beirut prison left the international tribunal in the Netherlands with no suspects in custody after a four-year U.N. investigation into an assassination that triggered enormous political and sectarian turmoil in one of the Middle East's most volatile countries.

The tribunal's decision -- after prosecutors said there was not enough evidence to justify their continued detention -- could also have an immediate political impact. Lebanon is heading into a crucial parliamentary election on June 7 that pits a pro-Western faction headed by Hariri's son Saad against an opposition dominated by the militant Shiite Muslim group Hezbollah.

Saad Hariri's faction is struggling to hold onto its legislative majority. The opposition, which took up the cause of the four generals, could get a boost from their release.

The generals had been held since August 2005 for suspected involvement in the suicide bombing that killed Hariri and 22 others in Beirut in February of that year.

Former General Security chief Maj. Gen. Jamil al-Sayyed, the first of the generals to appear in public after their release, spoke to hundreds of cheering supporters outside his house.

He lashed out at authorities for what he called their "political detention," but said he does not seek revenge.

"Never since independence have we had such a conspiracy of this scale ... officers being imprisoned for four years without evidence or charge," al-Sayyed said, his voice rising as he spoke in front of a banner with a picture of the four generals.

Tribunal judge Daniel Fransen demanded that Lebanese authorities protect the generals after he ordered their unconditional release and said they should no longer be considered suspects.

Fransen said a key witness had retracted a statement that initially incriminated the generals, undermining the case against them.

Prosecutor Daniel Bellemare said in court he would not appeal. He said in a written submission this week that the "evidence available to him currently is not sufficiently credible" to keep detaining the four generals.

So far, Bellemare has not indicted anyone and has not identified any other suspects in the suicide bombing.

Hariri's son said he accepted the tribunal's decision.

"It a step in the course of justice," he told a news conference. "Many people won't like this. We must respect the law. Any decision taken we will accept."

"I don't feel any disappointment with the decision or concern about the fate of the tribunal," Hariri said, dismissing concern that the move could spell the end of the process.

His father's assassination sparked mass protests that forced Syria's army out of the country after about three decades of political and military domination by Lebanon's neighbor. As prime minister, Hariri, a billionaire businessman, was credited with rebuilding downtown Beirut after the 1975-90 civil war, and with trying to limit Syria's influence in the last months before his assassination.

Many blamed Syria for his killing -- an accusation that Syria denies.

Taking up the cause of the jailed generals, Hezbollah leader Hassan Nasrallah had opposed their detention without charges.

"It is a joyful day for the Lebanese people and a day of mourning for Lebanese judiciary," Hezbollah legislator Hassan Fadlallah said.

Fireworks and scattered celebratory gunfire erupted across Beirut after the tribunal announced its decision at a televised news conference.

The other three generals are: Ali al-Hajj, the ex-Internal Security Forces director general; Brig. Gen. Raymond Azar, the former military intelligence chief; and the former Presidential Guards commander, Brig. Gen. Mustafa Hamdan.

"We consider today the beginning of finding out the truth about who killed the martyr Rafik Hariri," al-Hajj said.

His wife, Samar, said, "I'm too numb, too happy," as supporters and relatives distributed sweets and danced outside their home to the beat of drums.

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Associated Press writer Mike Corder contributed from Leidschendam, Netherlands.