Police were dispatched to the venue in Thompson's Lane, between Bishop’s Waltham and Winchester, after a member of the public saw social media footage showing a break-in at 11.40pm on Monday.
Officers made four arrests in connection to the incident, with an ongoing investigation into objects being thrown at the animals and ‘significant damage’ caused to the site.
A 20-year-old man and a 22-year-old man from Fareham, as well as a 22-year-old man and a 22-year-old woman from Gosport, were arrested on suspicion of burglary.
They have now been released from custody and remain under investigation, according to a spokesman from Hampshire Constabulary.
Videos allegedly showing the break-in continue to circulate online, with one video seen by The News showinga giraffe hit in the head by what appears to be a lobbed plastic bottle.
Another video has an individual filming themselves as they startle a tiger, causing the animal to flee from its enclosure fencing.
A spokeswoman from the zoo called the videos ‘appalling’.
She said: ‘We are aware of the appalling videos being circulated online showing our endangered animals in distress and we continue to assist the police with their investigation.
‘Our animals are all safe and those affected are being carefully monitored and cared for by our expert animal teams.’
The zoo is calling for support as it asses the damage of the break-in and continues to struggle through Covid-19 restrictions that have left the venue closed for months.
The spokeswoman continued: ‘Marwell is a conservation charity and this has happened at a time we are facing the toughest challenge in our nearly 50-year history after losing more than £4m in revenue due to the coronavirus pandemic.
‘We are humbled by the messages of support from our community and the generosity of those who have donated to our JustGiving fundraising appeal, which is helping us to care for our animals during this unsettling time.’
Since its launch last March, more than 3,000 people have contribute to the zoo’s fundraising campaign, which has brought in over £96,000.