An explosion was heard by residents in the front yard of a Parramatta home last night.
Police said residents of a home on Oak Street woke to the sound of an explosion outside about 1130pm last night.
Police were called and a crime scene was established in the carport area of the home.
Early investigations suggest the item may have been thrown from someone walking past.
Police are asking for anyone who saw any suspicious activity on the street last night to contact them on 9897 4199 or Crime Stoppers on 1800 333 000.