Senior officials connected to the New Jersey governor, Chris Christie, were warned on the first day of the notorious lane closures over the George Washington bridge that the resulting gridlock was causing problems for police and emergency medical workers, but pressed on with the policy for another three days.

Among almost 2,000 pages of documents released on Friday by the state assembly is an email sent on the morning of 9 September to Bill Baroni and David Wildstein, the two Christie appointees to the Port Authority, the body which controls the bridge, who were centrally involved in ordering the lane closures.

The email was sent at 11.24am – just a few hours into the controversial change in traffic flow that has been blamed on the political vindictiveness of some of Christie’s team against the Democratic mayor of Fort Lee, the small town that sits under the bridge.

“Wanted you both have a heads up,” says the email, from a communications official. The borough administrator of Fort Lee had called to say that amid the increased congestion in the town “there were 2 incidents that Ft Lee PD [police department] and EMS [emergency medical services] had difficulty responding to; a missing child (later found) and a cardiac arrest.”

On Thursday it emerged that paramedics complained that they had been unable to reach a 91-year-old female resident of Fort Lee, who later died in hospital.

Despite having been made aware of the potential threat to life caused by delayed emergency vehicles, the documents show that Wildstein informed bridge officials on the following morning, 10 September, that he wanted to continue what he called a “test” for another 24 hours. The “test” involved reducing access lanes from Fort Lee on to the bridge from the usual three to one – a move seen as an act of revenge against Mark Sokolich, the town mayor, who had previously declined to endorse Christie for re-election.

Wildstein has been identified as the senior official who initially ordered the lane closures. A month before, he exchanged emails with Christie’s deputy chief of staff, Bridget Kelly, who told him: “Time for some traffic problems in Fort Lee.”

Both Wildstein and Baroni resigned from the Port Authority last month. On Thursday, Wildstein was forced to appear in front of a state assembly committee investigating “Bridgegate” – he refused to testify, pleading his fifth-amendment right to avoid self-implication.

Christie has apologised for what he said had been “stupid” and “deceitful” acts on the part of members of his staff, but insisted he had been unaware of their involvement. The scandal that has engulfed him over the past few days is seen as a critical threat to his presidential ambitions in 2016.

The huge batch of new documents also reveal the extent of anger, and potential hostility, shown by the New York side of the partnership that controls the George Washington, the busiest bridge in the world. The Port Authority is controlled jointly by the two states it connects, New Jersey and New York, and officials are appointed by their respective governors, Christie and Andrew Cuomo. The tension between the two sides is obvious.

An email sent on 13 September by Patrick Foye, Cuomo’s appointment as executive director of the Port Authority, to managers of the bridge expressed apoplexy at the traffic chaos imposed by his New Jersey counterparts. He called the decision to impose lane closures “abusive”, potentially illegal and dangerous to public safety.

“I am appalled by the lack of process, failure to inform our customers and Fort Lee and most of all by the dangers created to the public interest,” he wrote. Announcing that he was lifting the lane closures as soon as it was safe to do so, he added the chilling note: “I pray that no life has been lost or trip of a hospital – or hospice-bound patient delayed.”

He went on: “I believe this hasty and ill-advised decision violates Federal Law and the laws of both States.”

On Thursday, it emerged that the New Jersey US attorney, Paul Fishman, is investigating whether the bridge events “implicated” any federal laws. One possible legal route would be to invoke federal protections of inter-state commerce, a point touched upon by Foye in his email when he warned that the lane closures had “undoubtedly had an adverse effect on economic activity in both states”.

As reporters pored through the new documents to see whether they contained any new evidence that would cast light on the involvement or otherwise of Christie and his senior staff, the emails cast light on the human misery caused over the four days of traffic mayhem in Fort Lee. One note from a New Jersey official records “an unpleasant interaction with Fort Lee police chief and asst chief about congesting the borough, and preventing the smooth flow of emergency response vehicles throughout the borough. Their characterization was that the ‘test’ was a monumental failure. Fort Lee is not happy.”

A woman whose husband was 40 minutes late to a job he had just secured, having been unemployed for a year, complained that the Port Authority “doesn’t care about their customers and they are playing God with people’s jobs”.

Another member of the public phoned in threatening to contact the media and the White House if nothing was done to lift the congestion.

The New Jersey officials involved in initiating the lane closures appear to have gone to elaborate lengths to disguise the decision as a form of traffic study. On the third day of the lane closures, they put together a Power Point presentation titled “Reallocation of Toll Lanes at the GWB: An EARLY assessment of the benefits of the trial”.

The presentation included a graph showing traffic times over the bridge on 10 September compared with normal times.

Paradoxically, a light-hearted sign off at the bottom of one email, from a chief traffic engineer, says: “One text or call could wreck it all / www.distraction.gov”.