Two unknown men on bike threw acid over four women leaving three of them critically injured. The incident happened on Tuesday in the Shamli district of Uttar Pradesh.
The women, who are sisters and employed as teachers, were attacked as they were returning from the Hindu Inter-college in Kandhal following their UP board exam duty.
The victims Kamerjahan (26), Ayisha (25), Esha (23) and Sanam (20) were immediately rushed to hospital. Three were referred to a Delhi hospital after their condition was reported to be critical.
"We were coming back from work when two men came on a bike; they had their faces covered and attacked us with acid and ran away," one of the siblings told NDTV.
According to reports, the men used a water gun to splash acid on the women and fled the spot after the attack.
Police registered a case against the two men and are investigating the incident.
Tuesday's incident is among the spree of major acid attacks that took place this year. In February, a woman was injured in Pune after a 20-year-old engineering student splashed acid on her. Police arrested the offender and sent him to judicial custody till 2 April.
In Chennai, two women succumbed to injuries after they were attacked with acid in two separate incidents in February.
The report of acid attacks on the four sisters comes at a time when the government has revised the anti-rape law with new proposals of enhanced punishment for offenders in sexual crime cases. The revised law was tabled last month in the wake of the Delhi gang rape of a 23-year-old physiotherapy student.
The revised law categorises acid attack, stalking and voyeurism under criminal offences. It also awards death penalty to accused in rape cases if the victim died or was left in a vegetative state.