Two women were injured on Monday when the quad bike they were riding toppled over in Senglea, the police said.
The accident took place at Triq ix-Xatt Juan B Azzopardi at around 1pm.
The women, who are English, aged 28 and 23, were taken to Mater Dei Hospital by ambulance.
The 28-year-old suffered grievous injuries while the 23-year-old was slightly injured.
Police investigations are ongoing.