The crash happened at around 2pm on Sunday on the A458 near Buttington.
The road was closed for around three hours as a result.
A spokesman for Dyfed Powys Police has urged people with information to get in touch.
He said: "Police were called to a road traffic collision which occurred at about 2pm, Sunday, September 11, on the A458 near Buttington, Powys.
"Four vehicles were involved in the collision with two people being taken to hospital with what were believed to be minor injuries.
"The road was closed and reopened at about 5pm.
"Anyone with information that could help officers with their investigation is asked to report it to Dyfed-Powys Police, either online at: https://bit.ly/DPPContactOnline, by emailing firstname.lastname@example.org, or by calling 101."
People with information are asked to quote reference number DP-20220911-198.