An armed gang "callously" raped two young women who answered the door to their attackers, a senior police officer has told the BBC.
Ch Spt Sue Harrison said the attack was a 'despicable crime'
Chief Superintendent Sue Harrison said officers were working "flat out" to find the three men sought for Friday's attack in Saffron Walden, Essex.
Police had spoken to 70 residents and about 200 drivers by Sunday evening.
The women, both in their 20s, were confronted by the masked men when they went to the door at about 1930 GMT.
The men were wearing elongated skull masks similar to those worn in the horror film Scream.
Police in Saffon Walden are working 'flat out' on the case
On Sunday, Ch Supt Harrison told the BBC: "Three men who were wearing Scream-type masks entered the flat forcibly, ransacked the property, removed some items of property ... and very callously and viciously raped the two female occupants who were in the flat at the time."
The men, armed with knives and a handgun, taped their victims to a bed before raping them.
The men were all about 5 ft 4 in tall, an Essex Police spokesman said.
The ordeal lasted about 30 minutes and the women managed to free themselves and raise the alarm after the men left.
The rapists also stole property from the women's handbags.
Officers believe that the attackers drove away in a car at high speed.
Ch Supt Harrison said: "Essex Police's major investigations team is working flat out to apprehend these men who have committed an absolutely
Police believe that the attackers knew their victims and have warned people living in the local area to be on their guard, but not fearful.
A spokesman said: "Our feeling is it wasn't a random attack. We think that the men probably knew their victims, although their victims may not have known them."
Anyone with information is asked to call Saffron Walden police station on 01799 513232.