A package that exploded after being delivered to Northwestern University in Boston this week contained a note critical of Mark Zuckerberg, the CEO of Meta Platforms, which owns Facebook, according to CNN.

The memorandum also condemned the relationship between virtual reality developers and the university community, the American broadcaster reported, citing law enforcement sources.

A university employee who grabbed the package after receiving it on Tuesday was injured in the blast and taken to hospital for hand injuries, Boston police said. The second package, which was deemed suspicious, was neutralized.

Police said they are investigating the incident in cooperation with Boston Fire and EMS. Some evening classes were canceled yesterday, Tuesday, but the university will be open as usual today, according to the Northeast website. Authorities did not say who might have sent the package or why the Northeast was targeted.

CNN and Boston’s WCVB reported that the package contained a note criticizing Zuckerberg. Meta has developed the Horizon virtual reality platform. According to CNN, the author of the memo warns people against working with virtual reality developers. The WCVB reported that the memo was not signed and generally warned people not to do business with Zuckerberg.

The note was inside a sealed container that exploded on opening. Meta did not respond to a request for comment for this information.

Police at other Boston universities, including Harvard and MIT, have urged people to be especially vigilant and call authorities if they see a suspicious package.

In 2013, Boston was rocked by marathon bombings that killed three people and injured more than 260.

^{According to REUTERS, APE-MPE}