October 13, 2015 3:03 PM EDT

Toronto residents can bearly contain their excitement Tuesday as the giant panda Er Shun has given birth to twin cubs — one at 3:31 a.m. and another at 3:44 a.m. The video below shows the birth of the first cub, which starts wailing uncontrollably (so you may have to turn down the volume a bit):

Both unnamed newborns are about the size of a stick of butter. Zoo staffers are keeping their fingers crossed, hoping the young ones will survive the critical hours and days ahead. “At this time Zoo staff do not know the sex of the cubs and have not confirmed which panda is the father,” the zoo wrote in a press release. “It may be several months before we are able to determine the sex and paternity of the cubs.”

Write to Olivia B. Waxman at olivia.waxman@time.com.

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