AP
In this image taken from TV an armed member of the security forces stands guard as emergency services attend the scene after a explosion in a main metro station in Brussels on Tuesday, March 22, 2016.
A statement from the Amaq Agency, which distributes news about ISIS (which is also known as the Islamic State, ISIL, or Daesh) says that ISIS fighters carried out the bombings that targeted an airport and a metro station, killing dozens.
The statement cites Belgium's involvement in a US-led anti-ISIS coalition.
It's likely that the claim comes from ISIS itself, according to Charlie Winter, an expert on jihadist propaganda and a senior research associate at Georgia State University's Transcultural and Violence Initiative.
"A'maq is an official media outlet - a claim through A'maq is a real claim," Winter told Business Insider in an email. "Of course, they may be exaggerating level of involvement."
Rita Katz, an expert on ISIS propaganda and co-founder of the SITE Intelligence group, also confirmed the statement's authenticity to Business Insider.
Winter cautioned, however, that there is no claim in Arabic yet for the attacks and that the Amaq statement was written for a Western audience.
J.M. Berger, an expert on terrorist social-media use and coauthor of the recent book "ISIS: The State of Terror," noted that Amaq's claim "doesn't offer details that suggest insider knowledge" about the Belgium plot.
The Amaq statement was timed to another statement from another ISIS-affiliated channel on the secure messaging app Telegram, which ISIS is known to use to distribute statements and propaganda.
The statement, from a channel that distributes ISIS news in English, implored subscribers to post tweets using the hashtags #Bruxelles, #Brussel, and #Brussels. The statement said it was "top priority" for ISIS supporters to "fill our stuff into the Brussels hashtag on Twitter."
Earlier in the day, other ISIS channels had begun to coordinate a social media response to the attacks, providing templates of tweets for followers to send out.
This post will be updated.