At least two Katyusha rockets fired from south Lebanon exploded in northern Israel on Thursday morning, leaving two people lightly wounded and a number of others suffering from shock.

The rockets struck the Nahariya area at around 8 A.M., one of them scoring a direct hit on the roof a nursing home in the city.

A Hezbollah minister in Lebanon's Cabinet has denied any involvement by the militant group in the firing of the rockets. In 2006, Hezbollah guerrillas in Lebanon fired almost 4000 rockets at Israel during the Second Lebanon War.

Labor Minister Mohammed Fneish told The Associated Press that Hezbollah was not aware of the rockets targeting Israel Thursday.

Israel Defense Forces troops immediately fired five artillery shells at Lebanon in response to the rockets, an Israeli security source said. A military spokesman said Israel aimed "a pinpoint response at the source of fire."

About two hours after the attack, the rocket alert sounded again and two more Katyushas were reported near Nahariya. After an initial investigation, it became clear that the alert had been a false alarm.

This was the first instance of Katyushas being fired from Lebanon onto Israeli territory since the Israel Air Force began its offensive against Palestinian militants in the Gaza Strip on December 27.

The Lebanese government decried the attack as a clear violation of the latest United Nations cease-fire resolution and said it was determined to find out who had fired the rockets.

"Prime Minister Siniora regards what happened in the south as a violation of the international resolution 1701 and something he does not accept and Siniora called for an investigation into the incident," his office said in a statement.

Information Minister Tareq Mitri said he did not believe the Islamist Hezbollah, which is backed by Iran and engaged in a month-long war with Israel in 2006, was behind the attack.

"Hezbollah assured the Lebanese government that it remains engaged in preserving the stability in Lebanon and respects Security Council resolution 1701," the head of Mitri's office, Toufic Yannieh, quoted the minister as saying

Henry Carmeli, the manager of the Nahariya nursing home hit in the rocket fire, told Haaretz that the elderly residents were in the dining room waiting for breakfast at the time of the attack.

"The fact that all of the seniors were there saved many lives, because we saw that the strike caused heavy damage to the rooms on the second floor [where the residents sleep]," said Carmeli.

Carmeli added that many of the residents suffered shock and one sustained a broken leg.

Shlomi Regional Council head, Gabi Na'aman, told Channel 1 that local residents have been told to open their bomb shelters and that school has been canceled.

Lebanese security sources said that schools in south Lebanon were closed, however, due to fear of Israeli reprisal.

Intelligence officials had warned about possible rocket attacks from Lebanon prior to the Israel Defense Forces air and ground offensive was launched in Gaza almost two weeks ago.

In recent days, the IDF had raised its alert level on the northern front, based on information that the warnings will be realized.

No claims of responsibility for rocket fire.

No organization has yet claimed responsibility for the rocket fire. Based on past experience, it appears likely that a Palestinian organization, inspired by but not connected to Hezbollah, fired the rockets.

Lebanese security sources said they felt it was unlikely Hezbollah fired the salvoes. Hamas sources in Lebanon denied involvement.

Hezbollah has operated similarly during previous periods of escalation: In the past, it has allowed the Popular Front for the Liberation of Palestine leader Ahmed Jibril to take the lead in staging attacks against Israeli or American targets.

Israel has been preparing for the possibility of Hezbollah igniting a second front, saying it would retaliate massively.

The cabinet also had a northern front in mind when it approved a call-up of thousands of IDF reservists last week.

Hezbollah leader Hassan Nasrallah on Wednesday warned that should Israel attack Lebanon, it would suffer an even greater defeat than the one he claimed it suffered in 2006.

"We are prepared for every possibility and are ready for all aggression... The Zionists will discover that the war they had in July was a walk in the park if we compare it to what we've prepared for every new aggression," Nasrallah said, referring to the Second Lebanon War.