ISLAMABAD >> Pakistan said Wednesday it will avenge those killed by India’s missile strikes that New Delhi called retaliation for last month’s massacre of Indian tourists in India-controlled Kashmir. Pakistan called the strikes an act of war and claimed it downed several Indian fighter jets.

The missiles killed 31 people, including women and children, in Pakistan-administered Kashmir and the country’s Punjab province, Pakistan’s military said. The strikes targeted at least nine sites “where terrorist attacks against India have been planned,” India’s Defense Ministry said. Two mosques were hit.

Pakistani Prime Minister Shehbaz Sharif said his country would avenge the dead but gave no details, fanning fears of all-out conflict between the nuclear-armed rivals. Already, it’s their worst confrontation since 2019, when they came close to war.

A heavy exchange of fire continued to follow the missile strikes, and officials in each country confirmed people killed. Sharif commended the armed forces for shooting down five Indian jets, which he said were hit after they fired their missiles but while still in Indian airspace.

There was no comment from India, but three planes fell onto villages in India-controlled territory, according to police and residents.

Tensions have soared between the neighbors since the April attack in which gunmen killed 26 people, mostly Indian tourists. Some survivors told Indian media that gunmen in some cases singled out Hindu men and shot them at close range.

India accuses Pakistan of being behind the attack, which was claimed by a militant group calling itself Kashmir Resistance. India has said the group is linked to Lashkar-e-Taiba, a disbanded Pakistani militant group that New Delhi long accused of being backed by Pakistan.

Islamabad denies involvement.

India and Pakistan have fought two of their three wars over the Himalayan region of Kashmir, which is split between them and claimed by both in its entirety.

In the wake of the massacre, the rivals have expelled each other’s diplomats and nationals, closed their borders and shuttered airspace. India has also suspended a critical water-sharing treaty with Pakistan.

“Pakistan has every right to give a robust response to this act of war imposed by India, and a strong response is indeed being given,” the prime minister said, and later accused India of acting out of arrogance.

The country’s National Security Committee said Pakistan reserves the right to respond “in self-defense, at a time, place and manner of its choosing.”

The statement said the strikes were carried out “on the false pretext of the presence of imaginary terrorist camps” and said they killed civilians. The prime minister said he had attended the funeral of a 7-year-old boy.

South Asia analyst Michael Kugelman said the strikes were some of the highest-intensity ones from India on its rival in years and that Pakistan’s response would “surely pack a punch as well.”

“These are two strong militaries that, even with nuclear weapons as a deterrent, are not afraid to deploy sizeable levels of conventional military force against each other,” Kugelman said. “The escalation risks are real.”

In 2019, the countries came close to war after a Kashmiri insurgent rammed an explosive-laden car into a bus carrying Indian soldiers, killing 40. India responded with airstrikes.

U.S. President Donald Trump called the escalating conflict “so terrible” and urged both sides to stop the violence.

U.N. Secretary-General Antonio Guterres called for maximum restraint because the world cannot “afford a military confrontation” between India and Pakistan, according to spokesperson Stephane Dujarric.

Neighboring China also called for calm. Beijing is the largest investor in Pakistan by far and has multiple border disputes with India, including one in the northeastern part of the Kashmir region.