Protesters in parts of India set train coaches and vehicles on fire, blocked roads, and threw stones at the police to protest a new short-term government recruitment policy for the military.

On Thursday, military aspirants had torched some compartments of three trains, and 125 protesters were arrested, reported the Hindustan Times newspaper. Protesters gathered again on Friday, setting fire to coaches in at least two stations in the eastern state of Bihar and disrupting rail services, police said.

Protesters emptied the coaches before setting them on fire. Several trains were subsequently delayed. 

In the states of Bihar, Madhya Pradesh and Rajasthan, police used batons and tear gas, and fired shots in the air to disperse the protesters who had taken to the streets and damaged government buildings. Protests were also seen in the southern state of Telangana and in the capital city, Delhi. 

A 19-year-old was killed and at least 15 people were injured during protests in Telangana's Secunderabad. 

In Bihar, which was worst-affected, nearly 25,000 police were deployed in eight districts, police officer SK Singhal told AP news agency. 

"They have blocked trains in 10 places today," said Sanjay Singh, a senior police official in Bihar, to Reuters on Friday.

Indian Defense Minister Rajnath Singh on Tuesday announced an overhaul of its military recruitment process, known as the "Agnipath scheme," which led to these protests. 

What is the Agnipath scheme?

The "transformative" scheme seeks to hire more people on short, four-year contracts. Aspirants between the ages of 17 1/2 to 21 will be eligible for the plan, as the government wants to have younger and fitter people in the army, navy and air force. 

The armed forces aim to recruit about 46,000 people under the new system this year.

Military officials said the new system would help bring down the average age of the armed forces. In the army, the average age would drop from 32 to 26, reported business daily The Economic Times. 

"[This idea] will have a positive impact on armed forces human resource management," Admiral R Hari Kumar from the Indian Navy said on Zee News.

After four years of service, only 25% of the recruits, known as "Agniveers," will be retained in the regular cadre based on merit, willingness and medical fitness. They will then serve for a full term of another 15 years. The remaining candidates will be demobilized with an exit package and other benefits, according to the plan. 

But many potential recruits object, saying they should be allowed to serve longer than four years. Protesting aspirants have also demanded clarity about exams conducted in 2019 and 2020, since there has been a hiring freeze for over two years. 

After the protests, the government has decided to change the age limit from 21 to 23 in a one-time waiver.

Opposition parties and some members of Modi's ruling Bharatiya Janata Party say the system will lead to more unemployment. Politician Rahul Gandhi from the Indian National Congress Party said on Twitter, "The BJP govt must stop compromising the dignity, traditions, valour & discipline of our forces."

VP Malik, a retired Indian army chief, said the youths' disappointment was understandable. "The government and the armed forces have to do more work on their outreach to justify and explain the scheme to the youth,'' he said in an interview with The Times of India newspaper.

Edited by: Alistair Walsh