An industrial-strength firework has been used to blow up a telephone box in a residential area.
Bomb squad officers have made the area safe in Military Road, Folkestone, and a police investigation is under way.
A second kiosk in St Leonards Road, Hythe, was also burnt out with more conventional fireworks.
The two attacks in east Kent follow similar incidents in north Kent - police say the culprits need to be caught before someone is killed.
Police were called to the first attack in Folkestone at 2115 GMT on Wednesday.
Emergency teams tackled the second attack in Hythe, less than an hour later, at 2208 GMT.
Roof 'blown off'
Inspector Roy Kingston said: "The kiosk in Folkestone has been badly damaged - the glass has shattered and the roof has been blown off.
"The telephone kiosk in Hythe is intact but has been quite badly damaged by smoke."
He added: "These are in residential areas - it is quite possible that anyone could be walking past these kiosks when this happens.
"When the firework goes off, all the glass panes shatter, sending shards down the road. It's a type of bomb."