Residents have been evacuated and told to 'stay away from windows' after a gunman was spotted in Havering, east London.
Anyone living in Snowdrop and Bluebell Court is being evacuated to South Street Community Centre due to a "serious incident".
A man was threatening to shoot himself at a home in Plough Court, Broadis Way in Rainham.
He was detained under the mental health act at 2.15pm but the area has been evacuated.
Explosive officers have been sent in to an address nearby.
It is understood that 90 families - as many as 300 people - have been told to leave their homes.
A nearby petrol station is believed to have been closed.
Residents have been told they may not be able to return home from anywhere between an hour to overnight.
The Mardyke Community Centre has been opened up as an emergency station to provide tea, coffee and shelter to residents.