TUNIS, Tunisia -- Rioters hurled stones at trams and government buildings in Tunisia's capital on Thursday in defiance of increasingly tough government attempts to quash more than three weeks of rioting by youths angry about joblessness.
Overnight, police opened fire and killed four people who defied a government curfew in several towns, opposition members said, driving up a death toll already in the dozens. Looters in the Bizerte region raided a supermarket, pharmacy, clothing shops and a bookstore amid chaos, said union leader and human rights advocate Souad Ghousami, a member of the opposition PDP party.
Security forces appeared unable or unwilling to intervene, and the military appeared to focus its efforts on public buildings, she said. Many youths were taken into custody.
The unprecedented violence has revealed deep anger against autocratic President Zine El Abidine Ben Ali, who has clamped down on civil liberties, jailed opponents and tightly controlled the media during 23 years of rule in the Mediterranean tourist haven where unrest had been rare.
Ben Ali announced plans to give his third television address since the start of tensions later in the day.
The government's death toll stands at 23, while opposition figures and witnesses say it is more than 50, including the deaths overnight near Tunis and in the northern region of Bizerte. French and Swiss citizens visiting their native country were among those killed, the two European governments said.
In the capital, which until this week had been spared the violence erupting in provincial towns, rioters threw stones at Metro trains, forcing them to return to their depot. The Interior Ministry building and a municipal services building were among targets of protesters' anger.
Near the French Embassy, hundreds of protesters, some throwing rocks, clashed with undercover officers and riot police who fired tear gas in an effort to disperse them, a witness said.
Police were deployed on major thoroughfares in the capital, and stores were shuttered -- as was the central souk, or market.
The European Union has complained about the disproportionate use of force in a country that is considered an oasis of calm compared to its neighbors, Algeria and Libya.
Ben Ali has gone on national TV in an appeal for calm and to pledge job creation, but his efforts have not done much to stop the unrest.
Mourad Yacoubi, an academic and member of the PDP party, said two people were shot to death and another was severely wounded after being hit by gunfire in the Al Intilaka housing project outside Tunis.
To the north, in the town of Menzel-Bourguiba in Bizerte, a young man, Khaled Ben Abderrahmane Mathlouthi, was also killed, said Ghousami.
Ghousami said another person, Skander Khlifi, was shot and killed in the nearby town of Sekma, where two others were also rushed to the hospital with injuries to the stomach and shoulder.
Amid complaints about a lack of openness, the government opened a media hotline, but calls to the line went unanswered on Thursday.
The Swiss Foreign Ministry said Thursday a woman with dual Swiss-Tunisian citizenship died in unrest in northern Tunisia. Swiss radio reported the woman was killed by a stray bullet while watching a protest a day earlier.
Another victim was a professor of computer science in France, at the University of Technology at Compiegne. University spokeswoman Nadine Luft said Hatem Bettahar had taught there for a decade and had traveled to Tunisia for vacation to see his mother.
Slah Nebti, a Tunisian teacher, said Bettahar was shot to death Wednesday by police in a protest in the central city of Douz. He filmed a video of the shooting's aftermath and posted it to Facebook: It showed Bettahar lying in a pool of blood, and the crowd shouting "God is Great!" in Arabic.
The French Foreign Ministry said it was looking into the circumstances of Bettahar's death.
Ben Ali, 74, has maintained an iron grip on Tunisia since grabbing power in 1987 in a bloodless coup, repressing any challenge to a government many see as corrupt and intolerant.
The image of stability and religious moderation helps draw millions of mostly European visitors a year to the Mediterranean beaches of this small North African nation, making tourism the mainstay of the economy. The economy's weak point is unemployment -- officially nearly 14 percent, but higher for youths.