LAHORE, Pakistan (AP) — A clash between Pakistan authorities and thousands of protesters marching in support of Palestinians killed at least five people including a police officer and injured dozens of other officers on Monday, police and witnesses said.

Punjab Police Chief Usman Anwar said demonstrators opened fire on authorities, killing the officer and wounding others. Police said three protesters and one passerby also died in the clashes before the demonstrators were dispersed.

The march was organized by political party Tehreek-e-Labbaik Pakistan, or TLP, which said in a statement that hundreds of rally participants were injured and the casualty figure was high among its supporters.

Videos released by TLP on Monday showed several vehicles burning, including a truck carrying party officials who were leading what they have called the “long march,” which started in eastern Pakistan on Friday with demonstrators planning to march from Lahore toward the capital, Islamabad.

The march has resulted in violence between authorities and demonstrators. Police arrested more than 100 people during a protest Saturday.

The latest clashes Monday began when protesters tried to remove shipping containers placed by police to block roads. Supporters clashed with police in Lahore and later camped in the nearby town of Muridke before resuming the march.

Before dawn Monday, TLP distributed a video of party chief Saad Rizvi urging security forces to stop firing and saying he was ready to negotiate. Gunfire could be heard in the background as Rizvi addressed supporters.

Rizvi was among the wounded Monday, TLP said. There was no information on his whereabouts and police said a search was underway to trace and arrest demonstrators and protest leaders who were hiding in nearby neighborhoods.

The demonstrators were determined to stage a pro-Palestinian rally outside the US Embassy in Islamabad and police came under fire when they launched an operation to disperse the crowd, according to Anwar, who said they were still assessing the damage.

The US Embassy issued a security alert last week ahead of the march, warning of possible disruptions and urging US citizens to exercise caution.

The TLP, known for staging disruptive and sometimes violent demonstrations, has drawn mixed reactions online. Some in Pakistan have accused the government of overreacting to the march by blocking major roads even before the protest began.

Pakistan Deputy Interior Minister Talal Chaudhry said over the weekend that he failed to understand why TLP opted for violence instead of celebrating peace in Gaza.

TLP gained prominence in Pakistan’s 2018 elections by campaigning on the single issue of defending the country’s blasphemy law, which calls for the death penalty for anyone who insults Islam. Since then, the party has staged violent rallies, mainly against desecration abroad of Islam’s holy book, Quran.

The party has held pro-Palestinian rallies in recent years in Lahore and other cities. This march was planned to travel toward the US embassy to express support for Palestinians.