Melissa McCarthy, Kristen Wiig and the Ghostbusters Cast

So who made this phone call?!

For several patients at Tufts Medical Center in Boston, Saturday turned out to be a day filled with unexpected visitors as Melissa McCarthy and her Ghostbusters co-stars surprised a few lucky individuals.

In full movie attire with matching backpacks, the cast including Kristen Wiig, Kate McKinnon and Leslie Jones entered hospital rooms to talk with patients and their respective families.

Some visits even called for an impromptu check under beds and some scans to make sure there weren’t any ghosts roaming through the halls.

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“They were a true delight to have today,” Brooke Hynes, VP of Public Affairs and Communications for Tufts Medical Center, shared with E! News Saturday afternoon. “They were so kind to all the kids and their parents.”

She added, “They took their time in each room visiting children as young as a few months to teens. We cannot thank them enough for their happiness and excitement they created.”

So what compelled McCarthy and the gang to visit? Turns out some of the kids at Floating Hospital put a sign in the windows that spelled out “Who ya gonna call?” The art display immediately grabbed the attention of the cast and crew filming outside.

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What came next was a surprise you only see in movies..or so we thought. 

Bridesmaids director Paul Feig continues to film the highly anticipated flick in Boston before it’s released to the public on July 22, 2016. His four leading ladies are joined by Chris Hemsworth, Michael K. Williams, and Neil Casey.

Dan Aykroyd also confirmed a cameo role by tweeting (and deleting): “On GB set shooting my scene with funny beautiful Kristen Wiig lady GB’S are adorable, hilarious and badass Exhilarating! #ghostbusters.”