A pregnant woman was among three people targeted when bleach was thrown from a car in two separate attacks.
Greater Manchester Police said the corrosive liquid hit a man and a woman in the eyes on Ashton Old Road, Openshaw, Manchester on Friday evening.
Shortly afterwards, bleach was thrown at a second man on the same road by a passenger in a silver Ford Fiesta heading towards Audenshaw.
Police said those affected were "lucky" to escape serious injury.
Insp Cherie Dunn, of Greater Manchester Police, said: "I am so thankful that none of the victims of these senseless attacks has been seriously injured.
"We could easily have been dealing with life-changing injuries.
"Anyone thinking that throwing bleach at people is funny or that a crime like this does not have consequences couldn't be more wrong.
"The victims here were lucky. Bleach attacks could have had catastrophic consequences."