A student shared chilling photos trapped inside the Marjory Stoneman Douglas High School during the shooting

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Students evacuate Marjory Stoneman Douglas High School in Florida on Wednesday.

• A student barricaded inside one of the classrooms at Marjory Stoneman Douglas High School in Florida took photos of the scene amid an active shooter incident on Wednesday.
• At least 20 students were injured, local media reported.
• One person is in police custody, but the scene is still active. The FBI has arrived on scene and is investigating.

A student locked inside a classroom during a shooting at a Florida high school on Wednesday took photos and tweeted updates.

In one of the images, students can be seen sitting on the floor and texting on their phones.

"My school is being shot up and I am locked inside," the unidentified student said in a tweet. "I'm f---ing scared right now."

CNN and local station WSVN 7 reported that students still in the school are barricaded in classrooms and hiding in closets.

Business Insider was not able to verify the authenticity of the student's Twitter account.

Marjory Stoneman Douglas High School went on lockdown Wednesday afternoon after reports surfaced of an active shooter. At least 20 were injured, local media said. The high school is located in Parkland, Florida, about an hour north of Miami.

One person is in police custody, the Broward County sheriff's office said, but the scene remains active. The FBI has arrived and is investigating the incident.

The Coral Springs Police Department said on Twitter that students and teachers still inside the high school should remain barricaded until authorities arrive and give them further instructions.

At 4:25 p.m. local time, the student tweeted another photo that he was free:

CBS shared video from inside a classroom, as well.

WARNING: The video contains graphic, disturbing sound and images.

This story is developing. See our coverage for updates.