Hundreds of people attended a prayer vigil in Waterford for four members of the same family killed in an arson attack. Kim English, Philip English and two of their children, nine-year-old Jayden and 12-year-old Callum, died after their home in Birch Avenue was set on fire on Tuesday. The vigil took place at Sacred Heart Church on Wednesday, with prayers, songs and memories for the deceased. Gardaí said multiple searches were carried out on Tuesday evening. Vehicles and electronic devices were seized for technical examination, and detectives described the investigation into their murders as intense in nature and very active. Six members of the English family were sleeping when the home was attacked in the early hours of Tuesday. It is believed an incendiary device, likely a petrol bomb, started the blaze. Two children suffered severe injuries and were taken to a Dublin hospital, where both remained in critical condition on Wednesday. Fire crews were alerted at 05:13 local time and arrived to a well-developed fire at a two-storey house. A number of casualties were removed before the blaze was extinguished and the scene was handed to gardaí. Investigators believe the house was attacked by a person or persons unknown and that the fire was started deliberately. Detectives also appealed for anyone who was in the Birchwood housing estate between 04.30 and 05.30 on Tuesday morning to contact them. Detectives said they believe the attack is linked to organised crime and drugs-related intimidation. Ch Supt Anthony Pettit urged people who know the person or persons responsible to come forward, and the investigation continues. Waterford Garda Station is leading the probe into a multiple murder and arson attack, with inquiries ongoing and technical examinations underway.