A fire engine drives away from flames on the ridge, east of Silverwood Lake in Crestline, Calif., Sunday, August 7, 2016. (Photo by Terry Peirson/The Press-Enterprise via AP Photo)

Libyan forces allied with the U.N.-backed government fire a shell at Islamic State fighters' positions in Sirte, Libya August 15, 2016. (Photo by Ismail Zitouny/Reuters)

Londoners sleep on the platform and on the train tracks at Aldwych Underground station,London, during heavy all night Nazi bombing raids, October 8, 1940. (Photo by AP Photo)

A zoo employee carries three-month-old female giant panda cub, born to mother Liang Liang and father Xing Xing, on display to the public for the first time at the national zoo in Kuala Lumpur, Malaysia, November 17, 2015. (Photo by Olivia Harris/Reuters)

Visitors wear shirts with an image of former Chinese leader Mao Zedong at the Shanghai World Expo site in Shanghai, May 2, 2010. (Photo by Aly Song/Reuters)

A street artist makes soap bubbles in front of the Alte Nikolaikirche church at the Roemerberg square in Frankfurt am Main, western Germany, on August 12, 2018. (Photo by Frank Rumpenhorst/DPA/AFP Photo)

An Indian Royal Bengal tiger looks on at an enclosure on World Tiger Day at Alipore Zoo, Kolkata, India, 29 July 2019. Kolkata zoo authority added a new Tiger to the zoo for the visitors to mark the Tiger Day. Students of Kolkata are also taking part in an awareness campaign aiming to draw attention to the threats that tigers face due to habitat loss and poaching. (Photo by Piyal Adhikary/EPA/EFE)

Pakistani vendors carry animals in a bus for the upcoming Muslim festival Eid al-Adha in Lahore, Pakistan, Monday, August 5, 2019. Eid al-Adha, or Feast of Sacrifice, is the most important Islamic holiday and marks the willingness of the Prophet Ibrahim (Abraham to Christians and Jews) to sacrifice his son. (Photo by K.M. Chaudhry/AP Photo)