Children may be afraid to go to school following the Londonderry security alerts, a principal said.

On Monday a van was abandoned at one of the entrances to St Mary’s College girls’ school on an arterial route into the city.

Nearby elderly residents and young families were forced from their homes by the false warnings while police have been tackling vehicle hijackings.

Marie Lindsay, principal of St Mary’s College, said: “It was an anxious few hours from when we heard that a van or lorry was abandoned at one of the school entrances.

“We are worried the children may be coming into school this morning feeling anxious and feeling that it is not safe, we are going to work extra hard to make sure that they feel okay.

“We were also very worried when we heard that many residents were evacuated from the local area because we know that many of them are elderly and other young families and so on, to think of them being evacuated from their homes, it was a cold, cold night and it was really a big worry.

“We are very relieved and thankful this morning that we are able to have the school open and for the children to be in school as normal.”

Three hoaxes created disruption after a car bombing in the city on Saturday which was blamed on dissident republicans the New IRA.

Four out of five men held over the bombing have been released.

A 50-year-old man arrested on Monday remains in police custody.

Residents were forced to leave their homes in the vicinity of the security alerts on Monday, two of which involved masked men hijacking vehicles, while bomb disposal experts carried out checks.

Police Service of Northern Ireland District Commander Superintendent Gordon McCalmont said the impact on the communities from the scares could not be under-estimated and the force shared their “anger and frustration”.

“We are grateful to those in the community who worked with us to find temporary shelter for those evacuated and for the patience of the people of this city as we worked as quickly as possible to make sure it was safe for normal life to resume.

“We share your anger and frustration when incidents like this happen but our overriding priority will always be the safety of everyone in this city.”

In the first scare on Monday three men reportedly hijacked a white Transit van in the Circular Road area at around 11.30am before throwing an object in the back and abandoning the vehicle.

Army bomb disposal experts carried out a controlled explosion on the van.

Just over two hours later, at 1.45pm, police received a report that four masked men – one allegedly armed with a gun – had hijacked a postal delivery van on Southway.

Police said the two occupants were ordered to drive to Lonemoor Road and leave it there.

The third incident saw another abandoned vehicle in the city cause panic on Monday night.

Police attended Northland Road after an Asda delivery van was left parked across the road, stopping traffic in front of St Mary’s secondary school.

Elderly residents were evacuated from their homes in pyjamas as police attempted to secure the area.

Meanwhile, a controlled explosion was carried out on a suspicious object discovered in Belfast on Monday night.

PSNI Inspector Natalie McNally said Springfield Road and Lanark Way in north Belfast have reopened.