Sudanese security forces in pickup trucks opened fire Saturday on hundreds of mourners marching after the funeral of a protester killed a day earlier, the latest violence in a week of demonstrations calling for the ouster of longtime President Omar al-Bashir.

The man killed was a pharmacist from a prominent family, suggesting the heavy security crackdown could deepen discontent, spread unrest and upset the complex network of power centers al-Bashir relies upon to stay in power.

Three female protesters interviewed separately said dozens of pickup trucks and security forces surrounded them in a main street in the capital Khartoum before firing tear gas and live ammunition. It was not possible to independently verify their account, but Sudanese activists and international rights groups say government security forces have routinely used live fire against protesters, often aimed at the head and torso. One of the three women was waiting at a hospital where she said two relatives were being treated for gunshot wounds.

The violent crackdown that aims to quash Sudan’s most extensive street demonstrations in two decades could now actually be propelling them, activists said.

“The excessive use of force means that the regime is becoming bare of any political cover and it is declaring a war against its own people,” said Khaled Omar, a member of the Change Now youth movement, one of the groups calling for protests. “This will backfire internally, inside the regime itself and cause cracks within and lead to its collapse,” he said, voicing a forecast held widely among activists but one that is difficult to predict.

The protests, which erupted Sunday night, were initially triggered by the lifting of fuel and wheat subsidies. But over the past days demands have escalated to call for the resignation of al-Bashir, who has ruled for 24 years.

“The cars came from the back and the front while we were marching in the street,” another female protester said. “The tear gas was very strong. The people fled trying to escape, taking shelter inside homes,” she added.

The death toll from a week of protests is sharply contested. Amnesty International and the African Center for Justice and Peace Studies have accused the government of using a “shoot to kill” policy against protesters, saying they had documented 50 deaths in rioting on Tuesday and Wednesday alone.

Youth activists and doctors at a Khartoum hospital said that at least 100 people have been killed since Monday. Sudanese police have reported at least 30 deaths nationwide, including policemen. Official statements have often blamed unknown gunmen for attacking protesters.

“Repression is not the answer to Sudan’s political and economic problems,” said Daniel Bekele, Africa director at Human Rights Watch in a statement Saturday. “Sudan’s authorities need to rein in the security forces and make it clear that using excessive force is not allowed,” he added.

Activists have begun to compile pictures, names and personal details of each protester killed.

Although he maintains a strong grip on power, al-Bashir has been increasingly beleaguered. The economy has been worsening, especially after South Sudan broke off and became an independent state in 2011, taking Sudan’s main oil-producing territory. Armed secessionist groups operate in several parts of the country. And al-Bashir himself, who came to power as head of a military-Islamist regime after a 1989 coup, is wanted by the International Criminal Court over alleged crimes in Sudan’s western region of Darfur.