Emergency services have been called after a person is understood to have swallowed the synthetic radioactive chemical Americium.
Police fire and Paramedics from the London ambulance services have all been scrambled to Holland Park Road in West London this evening following the emergency call for help.
Americium can be found in small amounts in smoke alarmed but can also be used to make dirty bombs.
It is currently unclear if the person swallowed the substance on purpose. Specialist Hazmat officers from the LFB have also been mobilised to the incident that started unfolding at around 7.30pm on Monday.
The Met Police have been approached for comment