Bedfordshire Police said they were alerted to a strong smell of gas at a property in Buxton Road in Luton.
Officers discovered one man who was suffering from the effects of inhaling gas and a second man who was pronounced dead at the scene.
Hertfordshire: The family of an 18-year-old found dead after a party said they felt "utterly lost" without him.
Student Ben Walters, from Berkhamsted, died at an address in the town. Six people were arrested on drug offences following his death.