Two women have been left with serious injuries after an alleged hit-and-run incident.
The crash in Harris Avenue, in the Rumney area of Cardiff, was reported at about 01:50 GMT on Thursday.
South Wales Police said the driver did not stop and left the scene.
A 45-year-old woman from Trowbridge and a 35-year-old woman from St Mellons were taken to University Hospital of Wales, in Cardiff.
The scene was cordoned off by police and a collision investigation unit attended.
The force said on Thursday evening that a 34-year-old man has been arrested after being found in Beddau, Rhondda Cynon Taf.
He is being questioned on suspicion of drink and drug-driving and traffic offences at Cardiff Bay police station.