Software engineer Joe Lopez could be heard shouting at Nadella in the opening minutes Monday of the tech giant’s annual Build developer conference in Seattle before getting escorted out of the room. Lopez later sent a mass email to colleagues disputing the company’s claims about how its Azure cloud computing platform is used in Gaza.

Lopez’s outburst was the first of several pro-Palestinian disruptions at the event that drew thousands of software developers to the Seattle Convention Center. At least three talks by executives were disrupted, the company even briefly cut the audio of one livestreamed event. Protesters also gathered outside the venue.

Microsoft has previously fired employees who protested company events over its work in Israel, including at its 50th anniversary party in April.

Microsoft acknowledged last week that it provided AI services to the Israeli military for the war in Gaza but said it had found no evidence to date that its Azure platform and AI technologies were used to target or harm people in Gaza.

The advocacy group No Azure for Apartheid, led by employees and ex-employees, says Lopez received a termination letter after his Monday protest but couldn’t open it. The group also says the company has blocked internal emails that mention words including “Palestine” and “Gaza.”

Microsoft hasn’t returned emailed requests for comment about its response to this week’s protests. The four-day conference ends Thursday.