A tornado hit a gas drilling rig in the northern part of the U.S. state of Texas on Wednesday, reportedly leaving three workers injured.

Of the three victims, all sent to hospital, one was slightly injured, while the other two were in serious condition, local media reported.

In a statement, local police did no mention whether the drilling rig was damaged or not, but only said that the accident caused "extensive damage" to a structure used to house tools and other work equipment.

Nearby highways were shut down because of the debris from downed trees and flooding.

Severe storms battered Texas in recent days, killing at least 14 people in weather-related incidents, including seven in Houston. The death toll may climb as there are still 31 people missing in the Lone Star state.

In the neighboring state of Oklahoma, which was also hit by storms and tornadoes recently, authorities found on Wednesday two more bodies, bringing the death toll to at least six in the state.

Authorities have urged people of the two states to make preparations as more rains will come in the next few days.