Ordinary firearms would cause an aeroplane to depressurise if its hull is pierced.
From the newscientist.com
A more recent hypothesis suggests an air vent was left open, causing the cabin to depressurise.
From the independent.co.uk
But the pair took so long to don their spacesuits and depressurise the cabin that the moon was just emerging when they finally appeared.
From the nzherald.co.nz
Three Soviet cosmonauts died in 1971 when a faulty valve caused their Soyuz 11 capsule to depressurise at an altitude of 168 kilometres, shortly before re-entry into the Earth's atmosphere.
From the newscientist.com
More examples
Depressurize: decrease the pressure of; "depressurize the cabin in the air plane"
(Depressurisation) changing from a high pressure environment to a lower one (e.g. upon re-surfacing from a dive)