Ammon News - AMMONNEWS - A gunman who is suspected to have killed five people in three communities of Montgomery County, Pennsylvania, in the United States, has been surrounded by the police outside the city of Philadelphia.

The suspect is believed to have barricaded himself after killing five people on Monday at three different homes.

The local school district, citing police activity in the area, has ordered students and teachers to shelter in place until further notice.

Officials are referring questions to the district attorney's office, which did not immediately return messages left by the Associated Press news agency.

Nevada shooting

Meanwhile in Nevada, a wounded security guard shot back and killed a public transit passenger who opened fire earlier on Monday when he was kicked off a bus on the Las Vegas Strip, authorities said.

Investigators said a security officer contracted by the Regional Transportation Commission told a passenger to get off the bus due to a disturbance. The man then pulled a handgun and shot the security officer multiple times. The officer fired back, fatally wounding the suspect.

The guard was taken to a hospital and is in stable condition with injuries that are not life-threatening, according to authorities.

The shootings in Pennsylvania and Nevada comes days after three teenagers and a 20-year-old man were shot and wounded outside a Portland, Oregon high school when a gunman thought to have gang ties opened fire following a dispute.

*AP