ISLAMABAD -- At least nine people were killed and more than 20 others injured on Sunday as protesters clashed with law enforcement personnel outside the US Consulate in Karachi in Pakistan's southern Sindh province, officials said.

The clashes erupted when demonstrators tried to enter the consulate premises on Mai Kolachi Road in Karachi, prompting security forces to respond, according to Rescue 1122 Sindh.

The injured were shifted to nearby hospitals, many in critical condition, spokesperson Hassan Ul Haseeb told Xinhua.

Who opened fire was uncertain at the moment, the spokesperson added, saying most of the injured sustained bullet wounds.

Thirty people were brought to Karachi's Civil Hospital, six of whom were declared dead on arrival. Three others later succumbed to their injuries, a hospital official told Xinhua on condition of anonymity.

Sindh Chief Minister Syed Murad Ali Shah expressed deep sorrow over the loss of lives. He ordered authorities to conduct an impartial investigation.

The chief minister instructed police and administration to provide full security for gatherings and ensure the protection of lives and property.

Federal Minister for Interior Mohsin Naqvi termed the day as one of mourning for the Muslim world, Iran and Pakistan, urging citizens to remain peaceful.

"We stand with you. Please do not take the law into your own hands and record your protest in a peaceful manner," he said.

In a statement, the US Embassy in Islamabad said it was monitoring demonstrations at consulates in Karachi and Lahore, as well as potential protests at the embassy in Islamabad and the consulate in Peshawar. It advised US citizens in Pakistan to monitor local news, stay aware of their surroundings, avoid large crowds, and ensure STEP registration is up to date.

The protests follow the assassination of Iran's Supreme Leader Ayatollah Ali Khamenei in Saturday's coordinated US-Israeli airstrikes on Tehran.

In Lahore, hundreds of activists gathered outside the US Consulate, with police enforcing security measures. In Islamabad, authorities imposed Section 144, banning all gatherings, and warned of strict legal action against violators.