WASHINGTON: At least five people were killed, and two others still missing following a flash flood in the USstate of Pennsylvania, authorities have said.

The Upper Makefield Township Police Department said on Facebook on Sunday that "the flash flooding caught numerous motorists by surprise and many were trapped".

Upper Makefield is a township in Bucks County with around 8,800 residents, located about 56 km northeast of Philadelphia, the largest city in Pennsylvania.

The local police department stated that the area was hit by a torrential rainstorm which caused flash flooding along several areas throughout the township, Xinhua news agency reported.

"Search teams have been working tirelessly through very difficult terrain all morning, and this effort will continue through the afternoon and evening," said the department.

The department on Sunday morning announced that three people who were swept away by the flood were found deceased, and confirmed the fourth and fifth deaths later in the day.

Two children, including a 9-month-old boy and a 2-year-old girl, are still missing, according to the department.

The mother of the two missing children is among the five deaths in the flood. The family from South Carolina was visiting relatives in the area. They were on their way to a barbeque when their vehicles got caught in the flash flood. The woman's husband and a 4-year-old son were able to escape. The grandmother of the family also survived and was treated at a local hospital.

The Upper Makefield Township has declared a local disaster emergency related to weather. Local officials urged residents who experienced property damage at their homes or businesses to report the losses.