Mumbai, Feb. 2: A witness has given police the description of the man who threw acid on four passengers travelling by a local train in Mumbai on Friday.

The acid attack had come on a day two other passengers were assaulted on local trains criss-crossing the city, leading to widespread fear and protests by people. Shiv Sena chief Bal Thackeray has gone to the extent of saying women should carry arms while travelling on local trains.

The railway police have now put out the sketch of the man who, if preliminary reports are to be believed, had targeted his girlfriend but inadvertently hit three women and a man travelling in the same coach.

Shirley Thomas, Manasi Shringarpure and Sunita Prasanna are employees of ICICI Bank and Faizullah Rehmatullah is a businessman. Shirley, who suffered the maximum injury, is nearly eight months pregnant.

According to the witness account, the culprit in his early 20s is well built, with a round face and wheatish complexion, and sports a thin moustache; he was wearing a light-coloured shirt and blue trousers.

The attacker was apparently engaged in a heated discussion with the girl and flung the acid at her after she boarded the Malad-bound train at Bandra.

Though the railway police have launched a massive search for the man, they are pinning their hopes on the girl who was originally targeted. They have appealed to her to come forward with information on the culprit.

“We assure her that her identity will be kept strictly confidential if she provides us information on the attacker,” senior inspector Parshuram Jadhav of Bandra railway police said.

Srikanth Savarkar, the railway police chief, said: “The girl should come forward and help us in the investigation. She is the key person in the whole incident and she needn’t worry about her security.”

The description of the couple has been sketchy, at best, though some police officers have said they may be college students. The police have recovered the acid container.

“But everything will be of little consequence if the girl doesn’t turn up,” Savarkar said. The police are apprehensive about her safety as the attacker is still at large, he added.

Shirley’s family has said that neither she nor her colleagues saw the couple arguing. “She didn’t even see the person who flung the acid,” a family member said. “The baby is doing fine and is due by the end of this month,” he added. “But she is not being allowed to meet anyone as she still is in a state of shock.”

The family of the other two women also refused to talk about the incident.

The acid attack was the first such incident reported by the Western Railway in Mumbai. There have, however, been other ferocious attacks on passengers of late.

One of the worst was reported in 1998 when Jaybala Ashar, in her 20s then, was flung out of a running train. She lost her legs in the assault. Jaybala now works in the operations department of the Western Railway.

Two years ago, on August 14, a 16-year-old mentally challenged girl was raped in the last train to Borivli.

Around 3,500 policemen are said to patrol the suburban railway that carries around 65 lakh commuters on Mumbai’s western, central and harbour lines every day.