Officers were called to Salford Royal Hospital in Greater Manchester at 9.20pm yesterday, after a man made threats towards staff, police said.
A weapon was recovered and the man was detained on suspicion of possessing a firearm and false imprisonment. A woman was also arrested on suspicion of possessing a firearm. Both remain in custody.
Greater Manchester Police said no one was injured during the incident, and inquiries were continuing.
More top news
An inventor who built a submarine has told police that a missing journalist died onboard in an accident, and that he buried her at sea.
Want to see the moon appear to take a "bite" out of the sun? Here's some tips on how to do it without damaging your eyes.
Rugby star Matt Dawson has revealed how he required heart surgery after developing Lyme disease from a tick bite.