A boundary wall of Modern School, Barakhamba Road, collapsed early on Wednesday, causing no hurt but damaging a car.
The 8am incident could have led to several injuries had students or school staffers been close by, officials said.
The collapse was reported by the disaster control cell around 9am. In response, civic defence volunteers and fire tenders were sent to the site of the collapse.
The incident caused two electrical junction boxes to get tilted, which were later repaired.
If the school took some comfort in the lack of injuries, it received flak from the Delhi Disaster Management Authority (DDMA), which slapped it with a showcause notice for "posing serious threat, to the life and security of both the students as well as the general public of the area".
The notice, issued by the deputy commissioner of the New Delhi district, asks the school principal to appear in person on Monday to explain why timely and necessary action was not taken.
According to DDMA officials, if the school fails to explain the incident, penal action could be taken against the authorities.
The notice also directs the school to appoint a teacher in charge of the school's disaster management cell, who must take the necessary training.
"We have been asking them to submit their disaster management plan for the safety of the students. They did not do so despite several reminders. We have again asked them to prepare and furnish a plan in 10 day," said a DDMA official.
The school authorities maintained that repairs were on. "The wall which collapsed had been built around a tree. Over the years, its roots and heavy rain had weakened the wall. After the rains on Tuesday, the wall collapsed a day later," Lata Vaidyanathan, principal, Modern School, Barakhamba, said.
According to the officials, local residents and resident welfare associations had complained to the school about the wall but nothing had been done.