Two men were sprayed in the face with an acid-type substance outside a bus stop.
Emergency services were called to Redbridge Lane East, Ilford, at just after 10.30am this morning.
The fire service treated them with "copious amounts of water" and took them to hospital.
A cordon is in place.
A statement from the Metropolitan Police said: "The two male victims have been taken to an east London hospital.
"Their injuries are not believed to be life-threatening or life-changing.
"The substance thrown is being assessed."
No arrests have been made.
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