Elderly woman left for dead in Vic assault

An elderly woman found with serious head injuries in a pool of blood and surrounded by her yelping dogs is clinging to life as Melbourne police work to find how and why she was attacked.

The 77-year-old remained in a critical condition late on Friday, almost 24 hours after being found in a neighbour's driveway at suburban St Albans.

Another woman is in custody after being arrested near the scene. No charges have been laid.

The victim had set out to walk her dogs but was found at about 7pm on Thursday in Mandy Kaur's Willaton Street driveway.

"I just come from my job and I'm taking a shower after when I come from the shower. I saw some people in my driveway and the lady's on the floor," Ms Kaur told journalists.

"I just see the blood, because everything covered with the blood."

The victim was taken to Royal Melbourne Hospital in a critical condition.

"For anybody to have received those types of injuries, clearly a significant altercation has occurred," Homicide Squad Detective Inspector Tim Day said.

A passer-by helped the woman and alerted a local resident who then knocked on another neighbour's door.

"My dad initially opened the door and he (the man) said that there is an elderly lady next door on the ground," the neighbour said.

"(We) rushed over. I saw a lady on the ground and her two dogs circling her, yelping."

Police aren't sure how the victim was assaulted.

Investigators would like to get a version of events from the passer-by, a man aged about 50, of Middle Eastern appearance and wearing a dark jacket.

Anyone who saw the victim, alleged attacker or passer-by, or with CCTV or dash cam footage should contact Crime Stoppers on 1800 333 000.