A 22-year-old man has been charged with driving while disqualified after his car crashed into a couple in Christchurch last night, killing them, following a police pursuit.

Further charges may be laid against the man, who will appear in Christchurch District Court on Tuesday, Detective Senior Sergeant David Harvey said.

Norman Richard Fitt, 73, and Deidre Valerie Jordan, 67, were killed on their way home from the gym. The pair were regular marathon runners, winning gold medals in the 60 to 70-year age group at the South Island masters aerobics competition, and went for regular morning 10km runs before hitting the gym in the evenings.

Canterbury district commander Superintendent Dave Cliff told Radio New Zealand that police would be talking the victims' families through what happened in the accident.

"What we're doing over the weekend is the head of the inquiry is sitting down with the families to step them through what we understand about what has happened," said Mr Cliff. "We do find that grieving families want to know as much as possible about what happened to their loved ones."

The accused man, driving a blue Ford Mondeo, had allegedly been travelling at 89kmh in a 50kmh zone along Ferry Road when police began pursuing him shortly after 8pm.

His car went through several green lights before running a red on Fitzgerald Avenue and Gloucester Street, near the central city, striking the couple's small red Daihatsu Terios.

Mr Fitt is believed to have died instantly, while Ms Jordan died after being cut from the car.

Mr Cliff told Radio New Zealand police had so far spoken to 11 witnesses and would be speaking to others this weekend.

Bystanders described last night's crash as a "nightmare" as both cars became airborne and rolled about 100 metres.

The driver, seriously ill in intensive care, was under police guard in Christchurch Hospital.

The Independent Police Conduct Authority will oversee the criminal investigation conducted by Mr Harvey.

Yesterday's deaths bring to 13 those killed this year in police chases, including a triple fatal in Christchurch last month.

"My thoughts and my sympathies are very much with the families of the victims of this tragedy," Police Minister Judith Collins said this morning.

"My thoughts are also with the police officers who deal with the aftermath of this, and other horrific accidents resulting from drivers who fail to stop and cause so much devastation."

She warned motorists not to flee police.

"A very strong message needs to be sent that if they run, there is a good chance they or other innocent people will die," Ms Collins said.

While most New Zealanders stopped when asked to by police, "there is an element in our society that thinks it is okay to defy the law and run".

In the past six years, police have had four internal reviews of pursuit policies.

Police recorded 1280 pursuits between January 1 and July 22, with 199 ending in crashes.

A police report released in July recommended more staff training, limiting the number of vehicles involved in pursuits, expanding the abandonment criteria, and abandoning pursuits once an offender's identity was known so an arrest could be made later.

- NZPA, NZ Herald staff