One resident was treated in hospital for injuries sustained while trying to "capture" the horned deer even as locals crowded around the animal, hampering rescue efforts. The animal was finally tranquillised and captured around 6pm by a team from NGO Wildlife SOS.

The appearance of the sambar in the east Delhi locality has puzzled wildlife experts as the animal is usually confined to dense forests and its sightings near the capital are very rare. It is presumed to have come into the area along the banks of the Yamuna.

The rescue operation took more than an hour after nearly half the day was spent waiting for the rescue team to arrive. On spotting the animal in the park, residents had made frantic calls to the police from 9am onwards.

A 10-man rescue team reached at the spot close to 5pm with specialised equipment to capture the deer, which included tranquilizers and large nets. By that time, a large crowd had gathered in the area, making the rescue operation difficult.

"Large crowds can cause stress to the animal and it is more likely to retaliate, especially when it feels cornered. We had to be extra careful to ensure that the animal did not get scared and also ensure that people were safe. A safety net was placed on one side and we made the animal run towards it before tranquilizing it safely. The animal has been identified as a male sambar deer," said Harshad Solanki, wildlife SOS rescue coordinator.

Sambars are part of the deer family and native to the Indian subcontinent.

"It is quite surprising that a sambar was spotted so close to Mayur Vihar. They generally tend to stay in dense forests and feed on leaves and shoots instead of grass. It is also possible it may have used the Yamuna corridor, but it is a rare sighting in Delhi," said FaiyazKhudsar, scientist in-charge at the Yamuna Biodiversity Park.

Bilal Habib, wildlife biologist from the Wildlife Institute of India agreed. "Several sambar deer have been spotted in the Aravalis, but it is rare for Delhi. If it was seen this far up, then it may have come through Haryana using the river corridor," he said.

However, Delhi's chief wildlife warden and conservator of forests A K Shukla said several sambar deer have been spotted in the central ridge. He suspects the animal may have strayed out and got lost. "Once the animal strays and gets out of a forested area, it is easy for it to get lost. People and vehicles can startle the animal. We have spotted several sambar in Delhi and have translocated a few as well in the past to other states," said Shukla.

Dallupura resident Uday Singh, 50, suffered injuries when the animal "attacked" him in the early hours of Wednesday. Singh had tried to capture the animal. He was taken to the Lal Bahadur Shastri Hospital and released later.

"I and a couple of others saw the deer and we thought we could subdue it. After I climbed over the wall, the animal charged at me and I had to be taken to the hospital due to severe bleeding," said Singh.

The animal will be kept under observation and transferred to the Asola Wildlife Sanctuary after it is deemed fit.