A gag order on the investigation into an incident in which two Palestinian siblings were shot and killed after allegedly attempting to carry out a terror attack in April was extended for the fourth time on Monday.

The extension is set to last until September 27, taking the media blackout past 100 days in total.

Twenty-three-year-old Maram Abu Ismail and 16-year old Ibrahim Salah Tahah were apparently shot by civilian security guards at a roadblock in Qalandiyah. Police have delivered the results of the investigation to prosecutors but in a highly unusual occurrence, did not include a recommendation whether or not to indict any suspects.

The details of the investigation have been in the prosecution's hands for two months.

The gag order forbids publication of a security tape documenting the incident among other details and evidence. Police originally refused to publish the tape, on the grounds that it was part of the investigation material, but Israel police has released similar tapes in the past and even added subtitles to explain the videos and justify the actions of police officers.

According to security forces, Maram approached the roadblock with a drawn knife intending to use it in a stabbing attack. Her brother followed behind and also had a knife on his person that had not been drawn.

A police officer at the scene yelled for them to stop and discharged his weapon in the air. The two were then shot and killed by civilian security guards.

Palestinian eyewitnesses told Haaretz after the incident that the two were far away from the police officers and didn't understand the calls for them to stop, which were in Hebrew.

The siblings' attorney said that she hadn't received any updates from the police or the prosecution in the last few days and that, to the best of her knowledge, the investigation materials were still being analyzed by the prosecution.