Tehran, Iran - Forty days after the death of the young Kurdish woman Mahsa Amini in Iran, demonstrators took to the streets across the country to express their anger and grief.

Security forces reportedly fired on demonstrators in several cities.

In her hometown, people flocked to her grave along a main road, the Hammihan newspaper reported on Wednesday. Activists had previously called for nationwide protests on the day of mourning.

Shiite Iran traditionally observes 40 days of mourning after the death of a family member.

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In Iran's capital Tehran, security forces used tear gas against a demonstration by doctors. The doctors were rallying against the presence of security forces in the clinics, where participants of protests are also treated.

Witnesses confirmed a massive presence of police officers and checks on the main streets in Tehran. Many shops remained closed for fear of riots.

Clashes with security forces were also reported from Iranian universities on Wednesday as students also continued to protest. Videos on social media highlighted violence but could not initially be independently verified.

In many places, demonstrators also shouted slogans critical of the Islamic Republic.

Towards evening, people also came together in Tehran to sing exuberantly on the street. In the north of the metropolis, many women were seen without the obligatory headscarf, witnesses reported.

Security authorities had braced themselves for nationwide riots on the milestone day.

"It is not a time for mourning, but for anger," read a protest call for Wednesday shared on the web.

The popular rallying cry "Woman, life, freedom" was also heard. Students have often been at the center of the protests in Iran, also in past years.

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Meanwhile, the United States imposed new sanctions on the country's leaders for the crackdown on protests. The new measures are aimed at the commander of the Iranian Revolutionary Guards and his deputy, high-ranking officials such as the director of the notorious Evin Prison and members of the secret service, the US Treasury Department announced in Washington.

The US accuses them of overseeing organizations involved in the violent crackdown on protests and killings, including of children.

Weeks of protests in Iran were triggered by the death of the 22-year-old Amini. The morality police had arrested her for allegedly violating Islamic dress codes. She died in police custody on September 16.

According to human rights activists, more than 10,000 people have been arrested and at least 250 killed.