PHILADELPHIA — A mate piloting a tugboat involved in a deadly collision of a tourist boat and a barge last summer was consumed by a family emergency and on his cell phone at the time, a new government report on the crash revealed Monday.

The 34-year-old mate told a tugboat company manager he had learned that his young son had suffered a life-threatening emergency that day during a medical procedure, the National Transportation Safety Board report said. The mate, identified as Matt Devlin, made or received 21 calls on his personal cell phone from the time he took the wheel at noon until the 2:37 p.m. crash.

The barge struck a disabled amphibious vessel called a duck boat on July 7, killing two Hungarian students and plunging 35 other people into the Delaware River. The NTSB report does not analyze what caused the crash.

“The families in Hungary cannot understand how a tugboat operator can be using a cell phone when his boat is about to destroy a tourist boat,” said lawyers Peter Ronai and Holly Ostrov Ronai, who represent the families of the students killed.

The 4,400-page report released Monday also said the K-Sea Transportation mate did not assign a lookout on the high-sitting barge as it was being pushed from behind by the small tug.