Two women have been shot dead at a house in the sleepy seaside town of St Leonards in Sussex, police said.
Sussex Police said said it had launched a murder investigation.
Two other women - including one who is pregnant - were led to safety by officers and taken to hospital. Both were uninjured but suffering from shock.
Police were called to the scene in Bexhill Road at around 7.45pm on Friday. A 35-year-old man was arrested on suspicion of murder two hours later, and a gun was seized.
Witnesses reported seeing a number of police vehicles and a helicopter in the area. A road was also closed as the investigation took place.
Police said the victims, aged 32 and 53, were known to the suspect.
Detective Chief Superintendent Jason Tingley said: "Tragically two women... have died after being shot and our thoughts are with their family and friends.
"We are not looking for anyone else in connection with this incident but we are appealing for any witnesses to come forward."
Anyone with any information is asked to contact police on 101, quoting Operation Winlot.