Two men reportedly entered a property at Black Dog at about 11.30am and assaulted two women, resulting in both women being taken to hospital with serious injuries, along with one of the children present, but the child was uninjured.
The men were reported to have left the scene with a third person in a V-registration Mazda 626 car parked nearby.
Police later said that they believed that the chemical used could have been a cleaning product.
The women have now left hospital and are receiving follow-up treatment.
Police located the vehicle later that evening on May 29 and, assisted by armed officers, attended an address in Old School Close, Tiverton, at around 11.15pm.
During that police operation, a 43-year-old man from Crediton and a 32-year-old man from Tiverton were arrested on suspicion of assault.
Anyone who saw the V-registration Mazda 626 prior to May 29 is asked to contact police on 101, or email: [email protected], with information, quoting crime reference CR/047560/19.
Information can also be passed anonymously to Crimestoppers via 0800 555111 or at: www.crimestoppers-uk.org .