Zanzibar , Tanzania ( CNN ) -- Two young British women were injured in an acid attack carried out by two men on a motorcycle on the east African island of Zanzibar , local police said Thursday . The women , who were attacked in Stone Town , the island 's historic center , had been working as volunteer teachers on the island , travel firm i-to-i Travel said . Stone Town is a UNESCO World Heritage Site popular with tourists . The Zanzibar government and a spokesman for the women 's families identified the victims as Katie Gee and Kirstie Trup , both 18 . The attack occurred Wednesday night as the women were walking unaccompanied along a street , said police Cmdr . Muccadam Khamis . The attackers , who did not take anything from their victims , left the scene on the motorbike , he said . Eyewitnesses said the acid was splashed on the women 's faces , chests and hands . The government condemned the attack and vowed to find the perpetrators . `` The event is a great tragedy , and an attack of this nature against a foreign citizen , has never happened here before , '' the Zanzibar government said in a statement . `` The government is appealing to the general public to assist in the arrest of the offenders and is offering a reward of 10 million shillings ( about $ 6,000 ) to anyone providing information leading to an arrest , '' the statement continued . The government also said it would regulate the purchase of acid and other related products , and warned that such attacks could seriously damage the island 's tourism industry , one of its main sources of funds . Police patrols will be stepped up in major tourist spots , officials promised . The women were given first aid treatment at a local medical center before British consular officials helped them reach a hospital in the city of Dar es Salaam , on the Tanzanian mainland , Khamis said . The UK Foreign Office is providing consular assistance and is in contact with the Tanzanian authorities , a spokesman said . Acid attack victim fights for justice . The women , who were in the final week of their trip when they were attacked , have been discharged from the hospital in Dar es Salaam , i-to-i Travel said in a statement . `` The motive for the incident is as yet not known and we will await the report from the local authorities in Zanzibar before any comment can be made , '' a company statement said . Russia 's Bolshoi Ballet director may lose sight after acid attack . `` The safety of our customers is of paramount importance to us and our own investigation will be launched as soon as it is possible to do so . '' Gee and Trup , both from London , are expected to fly out from Zanzibar on Thursday evening bound for the United Kingdom , the agency said . The women 's families asked for privacy until they 're reunited with their daughters . `` Both families are extremely upset and distressed about this completely unprovoked attack on their lovely daughters who had only gone to Zanzibar with good intention , '' relatives said in a joint statement . No one has claimed responsibility for the attack but it comes against a backdrop of rising extremist Islamist sentiment in the area . Last month , Tanzanian media reported that a businessman of Arab origin who had built a mall close to the American Embassy in Dar es Salaam was also injured in an acid attack . He is believed to be in South Africa for treatment . Zanzibar is a semi-autonomous part of Tanzania , a nation of just over 48 million people . According to the CIA World Factbook , the population of Zanzibar is 99 % Muslim , while the residents of mainland Tanzania are split roughly evenly among Christian , Muslim and indigenous beliefs . British authorities have said tens of thousands of British holidaymakers travel to Zanzibar every year and that this is the first such incident to affect foreign visitors to the island . i-to-i Travel says it aims to provide young travelers with `` meaningful travel trips '' and life-changing experiences by placing them as volunteers with community projects overseas run by non-governmental organizations . Its website advertises trips lasting from two to eight weeks teaching English in Stone Town . Actress in critical condition after acid attack in Pakistan . Journalist Farouq Karim reported from Zanzibar and CNN 's Nima Elbagir from Nairobi , while CNN 's Laura Smith-Spark wrote in London . CNN 's Bharati Naik and journalist Wande Makwaia contributed to this report .
NEW : The government will regulate the sale of acid , step up police patrols . Eyewitnesses say acid was splashed on the women 's faces , chests and hands . They were volunteering as teachers in Zanzibar , i-to-i Travel says . Their attackers were two men on a motorcycle , police say .