BBC News with Sue Montgomery.

The United Nations Secretary General Ban Ki-moon has warned that the situation in Gaza is perilous and has demanded that Hamas stop firing rockets to Israel. He urged the Israeli government to exercise restraint and respect international obligations to protect civilians.

Gaza is on a knife edge, the deteriorating situation is leading to a what downward spirals how which could quickly get beyond anyone's control. The risk of violence expanding further still is real. Gaza and the region as a whole can not afford any other full-blown war.

Mr. Ban is due to brief an emergency meeting at the UN Security Council on the crisis in Gaza later. Earlier, Israel's Prime Minister Benjamin Netanyahu said his country was ready to step up operations against what he called terrorist organizations in Gaza until rocket fire against Israeli targets stopped. The Palestinian politician Mustafa Barghouti said Hamas is acting in self-defense.

Hamas says it's ready to stop all attacks of that because everything they do as this here is in self-defense. And they obviously accept that the problem to here that I'm telling you is what Americans told us. Israel refuses to stop this operation and now they are preparing a ground operation which could lead this place into a huge massacre.

Iraq has warned the United Nations that Sunni militants have seized nuclear materials used by scientists in the city of Mosul. Here is Nick Bryant.

The nuclear materials were seized at Mosul Universities by ISIS rebels according to a letter sent to Ban Ki-moon by Iraq's UN ambassador. Some 40 kilograms of uranium compounds were taken which were being used for scientific research. The letter warns that despite the limited amounts involved, the materials could be used in the manufacture of weapons of mass destruction and enable what they calls terrorist groups with sufficient expertise to deploy them either separately or in combination with other materials to carry out attacks.

President Obama has urged parents in Central America not to send unaccompanied children on a dangerous journey through Mexico to try to enter the United States. He called on Congress to approve an emergency founding to deal with the problem and said he would consider a request made by Republicans to deploy members of the National Guard along the US-Mexican border.

We have countries that are pretty close to us in which the life chances of children are just far, far worse than they are here and parents who are frightened or are misinformed about what's possible all want to take extraordinary risks on behalf of their kids. The more that we can do to help these countries get their acts together, the less likely we are to have a problem at the borders.

BBC News.

Officials in the American state of Texas say six people including four children have been shot dead in the suburb of Houston. Thomas Foeman has more details.

The shooting happened at a house in the suburb of Spring, north of Houston. Police officers were called around six o'clock in the evening local time. One child and one woman were found alive at the scene and airlifted to hospital. The child died on arrival, the woman remains in a critical condition from gunshot wounds. Police pursued the suspect leading to a standoff near the scene of the crime. The gunman said to be in his thirties remained inside his car. After some late night negotiations, he eventually gave himself up. He's believed to be related to the victims.

Australia has rejected accusations by Sri Lankan asylum seekers that they were mistreated by Australian officials in the course of being handed back to the authorities in Sri Lanka. The Australian Immigration Minister Scott Morrison who's on a visit to Sri Lanka described the allegations as offensive. He defended the return of the 41 Sri Lankans after Australia intercepted their boat in the eastern Indian Ocean.

Police in Brazil say 12 people including the director of a World Cup hospitality company Ray Whelan have been indicted for illegal ticket selling. Public prosecutors will now decide whether to bring the case into court.

Argentine football fans have been celebrating their team's qualification for a place in the World Cup final. Argentina played a finally balanced semi-final against the Netherlands in which neither side managed to break down the other's defences. With the scores still nil-nil at the end of extra time the match was decided on penalties. The Argentine player Maxi Rodriguez took the decisive penalty.

This to take Argentina through on a margin of draw alls to two and it changed the act … behind the ball, when Maxi Rodriguez confirms the penalty!

And that's the bulletin from the BBC News.