Twenty Palestinians were killed during a stampede at a food distribution site run by the Gaza Humanitarian Foundation on Wednesday. The crowd surge occurred at a GHF site in the southern Gaza Strip, between Khan Younis and Rafah. Although nearly 700 Palestinians have been killed by the IDF on the roads leading to the distribution centers, this marks the first time that any deaths have taken place at an actual GHF site.

Witnesses said that GHF guards caused the stampede by using stun grenades and pepper spray against people trying to access the distribution center before it opened. The GHF claimed that the gate was open. Witnesses also said that Israeli troops fired at Palestinians on the road leading to the center. 

Foundation spokesman Chapin Fay, whose background is in media strategy and crisis management, told the Associated Press that a “large number” of people in the crowd were carrying pistols. He added that an American medic was stabbed.

According to the Gaza Humanitarian Foundation, 19 of the victims were trampled to death, while one was stabbed. The GHF, citing the Israeli military, claimed that Hamas militants had infiltrated the crowd in the hopes of sowing discord. The Gaza Ministry of Health, meanwhile, said that 17 people suffocated during the stampede, while the other three were shot. It also claimed that the GHF used tear gas on the crowd.

“The Americans were calling out on the loudspeakers, ‘Go back, go back.’ But no one could turn around because it was so crowded,” survivor Ahmed Abu Amra told the AP. “Everyone was on top of each other. We tried to pull out the people who were underneath, but we couldn’t. The Americans were throwing stun grenades at us.”

The stampede comes a day after 15 Palestinians, including six-week-old Yousef al-Safadi, starved to death as a result of the Israeli blockade on the Gaza Strip. The U.S.-backed siege has resulted in a chronic shortage of baby formula, which costs $100 a tub.