Officials at Dallas Sunset High School in Oak Cliff on Wednesday warned of incident in which students were approached by a group of people "in an attempt to lure them," before someone in the group fired a gunshot into the air and drove away.

The incident happened as Dallas police continued investigating a nearby string of robberies against middle school students from last week.

In the incident Wednesday, two students at Sunset High were heading to lunch from the school's classrooms across the street, Principal Claudia Vega wrote in a letter to parents.

A group of "unknown individuals" then tried to lure the two students, Vega said. As the students continued walking to the Sunset campus, someone in the group fired a gunshot and drove off into an alley.

The students were not injured, and the incident was reported to police.

Vega said the school will review its transitions between class periods and lunch for students who use the classrooms across the street. 

RELATED: 'I'll come back and kill y'all': Dallas middle school students robbed at gunpoint

RELATED: Dallas ISD warns about Oak Cliff student robberies

Over the weekend, Dallas ISD officials notified parents of a string of robberies targeting students, including the most recent incident on Friday, less than a block away from LV Stockard Middle School in Oak Cliff.

Stockard Middle School is about three miles from Sunset High School.

In the incident near Stockard, four men got out of a vehicle and demanded three boys' cellphones near the intersection of Poinsettia Drive and South Ravinia Drive, one victim's parent told WFAA.

"They said he laughed at them," Diane Guerra said. "He goes, 'If you tell anybody, I'm gonna kill you. I'll come back and kill y'all.'"

The three boys gave up their iPhones and ran to safety. They were not physically harmed. The suspects fled the scene.

Dallas police on Wednesday said they were also investigating another robbery on Friday involving two juvenile victims who were walking home in the 2000 block of South Franklin Street, which is several blocks away from Stockard Middle School.

Police said a suspect approached the victims with a weapon and demanded their property. The suspect then fled in a dark-color sedan.

Police said the robbery on South Franklin Street had "similar characteristics" to the reported string of robberies targeting Dallas ISD students.

Police provided parents and students a list of robbery prevention tips, including walking to school with a friend and avoiding a stranger's car if they begin asking questions. 

Read the full list of tips here.