An angry crowd of mourners fired bottles, rocks and other objects at Serbian Prime Minister Aleksandar Vucic Saturday at a ceremony marking the 20th anniversary of the Srebrenica massacre, where more than 8,000 Muslims were slaughtered in Bosnia and Herzegovina.

Vucic had come to the ceremony to lay flowers in commemoration of the event some have described as a genocidal incident when the disruption broke out. Thousands booed and whistled while some pelted the prime minister with objects, according to the Associated Press. He was hit in the face with a rock that broke his glasses, AP reported, citing Vucic’s associate, Suzana Vasiljevic.

Despite the violence, the prime minister later extended a hand of reconciliation via Twitter, saying in one translation, “We have to live together in peace.”

Bodyguards shielded Vucic with umbrellas as he and other dignitaries ran for their cars, according to CBC News. A video appearing to show the disruption was posted on YouTube Saturday, quickly attracting hundreds of views.

Serbia3 Serbia's Prime Minister Aleksandar Vucic shakes hands with Munira Subasic, the president of the Mothers of Srebrenica association, as she arrives to attend a ceremony marking the 20th anniversary of the Srebrenica massacre in Potocari, outside Srebrenica in Bosnia and Herzegovina, July 11, 2015. Photo: Reuters/Antonio Bronic

The Serbian interior minister described the attack on Vucic as an assassination attempt, Reuters reported.

Vucic in a former believer in so-called Greater Serbia, an ideology that powered much of the violence during the breakup of Yugoslavia, as the Irish Times reported. He has since embraced a pro-Western stance and supports Serbia’s effort to join the European Union.

Tens of thousands of people -- among them numerous world dignitaries such as former U.S. President Bill Clinton -- attended the ceremony, which included a funeral for 136 recently discovered victims whose remains were identified through DNA testing. The massacre, taking place during the Bosnian War in the eastern Muslim enclave, was the worst in Europe since the Holocaust.

The U.S. Immigration and Customs Enforcement (ICE) and the FBI issued a statement Saturday honoring the victims of the slaughter and vowing to hold accountable those who assisted who remain in the U.S. “The atrocities inflicted upon the victims at Srebrenica will never be forgotten,” said ICE Director Sarah Saldaña. “ICE will continue working with the FBI and other U.S. government partners to hold responsible those who assisted in the horrors at Srebrenica or who have lied to U.S. officials about their participation, in order to remain in the United States on a potential path to U.S. citizenship.”

The U.S. Embassy issued a statement condemning the disruption. “As Former President Clinton said in his remarks honoring the 20th anniversary of the genocide in Srebrenica today, it took courage for PM Vucic to attend the commemoration,” the embassy said. “The U.S. Embassy in Sarajevo condemns the subsequent attack on the Prime Minister. Many of the mourners were horrified by the violence and disheartened that it disrupted the solemnity of the anniversary.  The U.S. Embassy in Sarajevo shares that sentiment, and urges all to focus once again on the victims of the Srebrenica genocide and their families.”