A New South Wales police officer who was killed on duty when the car she was travelling in crashed into a tree in Sydney has been named as 20-year-old Mia Lay.

NSW police said the marked police car was travelling under lights and sirens along Gibbons Street in Redfern when it crashed at about 1.30am on Friday.

The officers were responding to a reported vehicle theft at Glebe.

Lay, a constable who had been with the force for 16 months, died instantly in the crash.

The 20-year-old police officer showed exceptional promise, the NSW Police Commissioner, Mal Lanyon, said.

“There is nothing I can easily say that takes the pain away but please know that Mia was a loved police officer,” he said.

Lanyon said it was too early to provide any specific details about the speed the police vehicle was travelling until the crash investigation was completed.

Paramedics treated the 24-year-old male constable who was driving before he was taken to hospital in a stable condition.

A crime scene has been established, and police have declared a critical incident.

The NSW police watchdog said it would monitor the force’s investigation into the crash to “ensure public confidence”.

The Law Enforcement Conduct Commission said it could not independently investigate the incident until NSW police finished its probe, and any coronial or criminal proceedings were over.

The premier, Chris Minns, and the police minister, Yasmin Catley, said their thoughts were with Lay’s loved ones.

“Today is a dark day, a very sad day. We’ve lost a beautiful, young, enthusiastic and … wonderful police officer,” she told reporters after meeting with her parents.

“Our police officers dedicate themselves to looking after others, and today the NSW Police family is mourning one of its own.”

Minns said he was also thinking of the officer injured in the crash and those who responded at the scene.

The NSW opposition leader, Kelly Sloane, said she was “heartbroken” by the news.

“(Lay) was out working while most of us were asleep, protecting the community,” she said.

Lay’s partner is also reportedly a serving police officer and has been offered support.

The police union paid tribute to their fallen colleague saying they were shocked by her death, days out from National Police Remembrance Day on 29 September.

“The death of this officer is sad evidence of the dangers they face,” the Police Association of NSW president, Kevin Morton, said.

“In the coming days, as the community learn more about this officer, it will become apparent what a special young person they were. We grieve with our members and commit to supporting their family into the future.”

Nearby Regent Street was closed in both directions on Friday morning between Lawson and Cleveland streets.