Two motorcycle-borne youths threw acid on four sisters, all teachers in a school in the Kandhla area of Shamli district of Uttar Pradesh on Tuesday.

The condition of one, Isha, was stated to be critical. She has been referred to Sir Gangaram Hospital in Delhi.

IG (Law and Order) R.K. Vishwakarma told journalists on Wednesday that the incident occurred at Chaar Khamba on the Kandhla bypass when sistersQamar Jahan, Sonam, Isha and Ayesha were returning home from Hindu Inter College.

Qamar was admitted to the Shamli District Hospital.

The two other sisters went home after receiving first-aid, the IG said.

No arrests have been made.The sisters, who reside in Sheikhjatgan Mohalla in Kandhla town area, are daughters of teacher Salim.