The Islamist extremist cell behind an earlier political assassination also killed a leftist Tunisian politician using the same weapon, a top security official announced Friday, according to AP.

Mohammed Brahmi was shot 14 times in front of his home within sight of his family on Thursday, plunging the country into a political crisis and unleashing demonstrations around the country blaming the government for the assassination.

Interior Minister Loutfi Ben Jeddou told reporters that ballistics tests on the 9mm bullets used in the attack showed it came from the same weapon used to kill opposition leader Chokri Belaid in February. The minister said a jihadi cell of 14 was behind that attack, four of whom were in custody.

The press conference came as thousands across Tunisia called for the government to resign.

Demonstrations raged around the country the night before, holding the ruling Islamist Ennahda Party responsible for the assassination and attacking local party headquarters. Police used tear gas in central Tunis and in the provinces to disperse the protests.

The slaying of Brahmi of the leftist Popular Current party raised fears of new chaos in the country that unleashed the Arab Spring. Tunisia is working toward enshrining a new constitution meant to lead the way to lasting democracy and so far has avoided the widespread violence and unrest as in Egypt and Libya.

Brahmi was a respected leftist politician and a strong critic of the Ennahda Party, which rules in a coalition with two other secular parties. There were no immediate claims of responsibility for his killing.

His party told The Associated Press it is postponing his funeral, initially planned for Friday, fearing it could inflame supporters on an already tense day. He will be buried Saturday in the same cemetery in Tunis as Belaid.

The main trade union called for a general strike Friday, closing down the airport, public transportation and most government offices as a new coalition of civil society and opposition parties called for the dissolution of the government and the national assembly.

In a statement published by Mosaique FM, several left wing and liberal parties announced the formation of a National Salvation Front calling for civil disobedience and a sit-in outside the national assembly until it and the government are dissolved.

There have also been reports of resignations by some members of the assembly, which was elected in October 2011 and charged with writing a new constitution and running the country. The constitution was expected to be completed and new elections held by the end of the year.

The new opposition front is calling for the formation of a national unity government charged with finishing the constitution and holding new elections.

In a statement late Thursday, Ennahda condemned the assassination as a “cowardly” act “targeting the revolution and national unity, and obstructing the democratic transition process.”

Much of the opposition, however, is holding Ennahda responsible for Brahmi’s assassination, much as it did Belaid’s, either because the Islamists have been unable to ensure security in the country or because they are actively collaborating with extremist elements to target their opponents.

The Interior Ministry has accused Islamist extremists of being behind the attack on Belaid and said it would announce the names of suspects shortly.

The U.S. State Department, the United Nations and Amnesty International called for an impartial investigation into the killings and for Tunisians to avoid reacting with violence.