The rockets hit the centre of the town of Kilis at around 1115 IST, the Dogan news agency reported. Ambulances were sent to the scene as police threw a security cordon around the area.
Dogan said one of the rockets hit a building used by Syrian refugees and two of those wounded were Syrian citizens.
Another person was wounded by the second rocket and police also evacuated a school nearby.
Kilis, where according to Turkish officials Syrian refugees now outnumber the native Turkish population, has been hit several times by IS fire.
More From This Section
In March, two people including a four-year-old child were killed by rocket fire there, while in January a janitor was killed and pupil wounded when IS fire hit a school.
Turkey has on occasion been accused by its western allies of not doing enough to combat the threat of IS, which captured swathes of Iraq and Syria right up to its border.
The latest attack comes after Turkish armed forces launched repeated artillery strikes in the last weeks on IS positions in Syria.
A fragile ceasefire backed by Turkey has taken effect in Syria, but the deal does not apply to territory held by the IS group and Al-Qaeda affiliate Al-Nusra Front.
Turkey has also been hit by attacks blamed on IS jihadists, including two deadly suicide bombings in Istanbul that targeted foreign tourists.