A participant in costume and make-up poses for a photo during a Halloween parade at Walibi park in Wavre, Belgium, October 31, 2018. (Photo by Yves Herman/Reuters)

This combination of April 15, 2013 and April 2, 2014 photos show a police officer clearing Boylston Street following a bomb blast near the finish line of the 2013 Boston Marathon, and pedestrians crossing at the same corner nearly a year later in Boston. (Photo by Charles Krupa/AP Photo)

An Iraqi woman grieves at the scene of a bomb attack in Jameela market in the Iraqi capital's crowded Sadr City neighborhood Baghdad, Iraq, Thursday, August 13, 2015. A massive truck bomb ripped through a popular Baghdad food market in a predominantly Shiite neighborhood in the early morning hours on Thursday, killing dozens of people, police officials said. (Photo by Karim Kadim/AP Photo)

A bulldog dressed as Marilyn Monroe poses for a photograph during the annual Tompkins Square Halloween Dog Parade in the Manhattan borough of New York City, October 24, 2015. (Photo by Stephanie Keith/Reuters)

David Nicholson, 21, surfs as "The Mask" during the ZJ Boarding House Haunted Heats Halloween Surf Contest in Santa Monica, California, United States, October 31, 2015. (Photo by Lucy Nicholson/Reuters)

In this composite image (L-R top row) Dok Haze, Douglas Child as Camp Dracula, Mongolian Laughing Boy, Tony Walls, Asia Sawika as Anastasia, (L-R bottom row) zombie bass guitar player Ozzy Jackson, sword swallower Hannibal Hellmurto, pickled person, Zoe Olivia Ellis and The Sinister Sisters, Steph Bates (L) and Steph Randall (R) pose for a photograph prior to a rehearsal of the Circus of Horrors' latest show The Night of the Zombie at the Wookey Hole Caves Theatre near Wells on October 23, 2014 in Somerset, England. (Photo by Matt Cardy/Getty Images)

David Nickerson, 24, rides a wave dressed as Mrs Doubtfire during the 7th annual ZJ Boarding House Haunted Heats Halloween surf contest. (Photo by Lucy Nicholson/Reuters)

A dog dressed in a costume takes part in the Pet's Halloween Day parade at Abtao Park in San Isidro, Lima, October 31, 2016. (Photo by Guadalupe Pardo/Reuters)