A 60-year-old woman who was walking with her older sister was fatally injured early Thursday when she was hit by an MBTA bus near an on-ramp to the Tobin Bridge in Chelsea, authorities said.

The victim was identified as Mary Pettiglio of East Boston, the MBTA Transit Police announced Thursday evening.

“The MBTA is deeply saddened by this tragic event, and we extend our condolences to Ms. Pettiglio’s family and loved ones,” Transit Police Superintendent Richard Sullivan said in the statement.

Sullivan said the pedestrian was struck aound 5:40 a.m. by an MBTA driver operating on bus Route 111, traveling inbound on Everett Avenue. He said the male driver was “experienced” and has worked for the MBTA for 12 years.


The bus operator, who was not identified, has been suspended. Transit police, State Police and the Suffolk district attorney’s are investigating, according to the statement.

Sullivan said the victim was accompanied by her 62-year-old sister at the time of the crash.

The bus and investigators stayed on the scene until about 8:45 a.m. when the ramp was fully reopened, officials said.

Sullivan said the driver would undergo drug and alcohol testing and won’t be allowed to operate a T bus until the investigation by Transit Police is complete. The bus was taken to Transit Police headquarters for a forensic examination, he said.

Correspondent Adam Sennott contributed to this report. Emily Sweeney can be reached at esweeney@globe.com. Follow her on Twitter @emilysweeney.

John R. Ellement can be reached at ellement@globe.com. Follow him on Twitter @JREbosglobe.