Police spokesman Prishantha Jayakody said they arrested two of the accused men yesterday after a witness raised an alarm and the authorities were looking for two more suspects.
"The victim has been admitted to hospital," Jayakody said adding that the men had attacked her when she went to a taxi stand to ask for directions after losing her bearings in the Mirihana suburb of Colombo on Wednesday night.
A women's rights group, Lak Vanitha, or Lankan women, said they were staging a demonstration later today outside a police station in the same area where the unidentified woman was attacked by the drivers.
"We have about 1,400 rapes recorded each year in Sri Lanka," Lak Vanitha chief Shanthinie Kongahage told PTI.
"The actual number should be much more. Most victims are afraid to report because of social stigma or out of fear of more violence," she said adding, "We are pressing the police to ensure a speedy investigation and a quick prosecution."
She said the international publicity surrounding the Delhi gang-rape last month had inspired her group to raise the issue locally and create more awareness in the local community.
"Lot of women are harassed by three wheel drivers," she said referring to the ubiquitous autorickshaws which have become an alternative to poor public transport.
"We need to take a stand and say enough is enough," she said.
The 23-year-old Indian gang-rape victim who died of her injuries has touched a nerve in neighbouring Sri Lanka where activists have expressed solidarity with Indian women facing sexual violence.