I don't think the government is that organized and that thoughtful to be honest. I think they're just winging it. One eye witness said he saw some kids with a device that looked like a DVD player with a fold out screen, and one of the kids was encouraging the other kid to plug it in, and when they did, it started popping and created a portal.
So my theory is this: The government has a portal machine (or many) and a government employee who works with these machines brought one home (for whatever reason) and his 14 year old "borrowed" it to show off to his friends. These kids were afraid to try it at home, so they decided to go to a public place with lots of people around, so they took it to the mall. That way if a creature comes through, they can scatter and only have to run faster than granny. The father discovered the device was missing and called in the cavalry, which is why the cops were already arriving at the mall by the time the people started running. They were looking for these kids. It also explains the official story of four kids having been arrested, they just didn't tell us the real reason for the arrests. When the kids plugged in the device, it started making popping sounds, which is why people thought they heard fireworks or gunshots (and conveniently provided an easy cover story for the police), but the popping sound was the sound of a portal being generated. Portal pops open, creatures step through, everybody runs.
The portal machine does not create a portal to another planet, but to another dimension. There's a video on YouTube of an ex-CIA operative who said a high ranking pentagon official told him not to mess with aliens because they are demons. Which would jive with demons living in a different dimension, on our earth, and a portal being required for them to step into our dimension, or vice versa. It also would explain why UFOs (and even Bigfoot) seem to be able to disappear and reappear at will, as though they're moving into another dimension. The jellyfish UAP from last week, was only visible using a thermal imaging camera, and others have said that the original "red vision" night vision cameras allowed pilots in Vietnam to see demons, which tells me that certain camera technology is able to see the other dimensions, as though a dimension is nothing more than a cloak, and the portal removes the cloak (which might explain the popping sound). Coincidentally, it's been said that night vision is "alien tech", recovered from alien spacecraft, so if night vision is required to see other dimensions, that would make sense.