A hospital's emergency department put patients at risk, a health watchdog has found.
Staff at Boston's Pilgrim Hospital used "unsafe" methods "to identify critically ill patients" which led to delays in their treatment, according to the Care Quality Commission (CQC).
Inspectors said they had to intervene and alert doctors to patients who needed immediate attention.
The trust's director of nursing Michelle Rhodes has issued an apology.
The CQC, which carried out the unannounced inspection on 30 November, said "the department felt overcrowded and chaotic".
Inspectors also said patients had to wait in corridors and ambulances, with "delays more than three hours for patients to be assessed by the medical team."
In one case, a child with suspected sepsis had to wait 75 minutes to see a doctor and was only seen by the consultant in charge after CQC staff alerted a nurse having reviewed the child's medical notes.
Concerns were also raised about staffing levels and the high number of locum workers.
In response, Ms Rhodes said: "We know that this report will be upsetting for our patients, public and staff to read and we would like to apologise to any patients who have not received the high quality care we would expect.
"This report by the CQC makes very difficult reading for all of us and we fully accept their findings.
"This is a position none of us want to be in."
The hospital, run by the United Lincolnshire Hospitals NHS Trust, has been in special measures since 2017.